Pennsylvania: Consolidated Chronology of State and County Boundaries

Pennsylvania Atlas of Historical County Boundaries

John H. Long, Editor; Peggy Tuck Sinko, Associate Editor; Gordon DenBoer, Historical Compiler; Douglas Knox, Book Digitizing Director; Emily Kelley, Research Associate; Laura Rico-Beck, GIS Specialist and Digital Compiler; Peter Siczewicz, ArcIMS Interactive Map Designer; Robert Will, Cartographic Assistant

Copyright The Newberry Library 2008

10 April 1606

King James I chartered two Virginia Companies, headquartered in different English cities, to establish colonies along the coast of North America, including islands within 100 miles and, by implication, extending inland 100 miles. The Virginia Company of London was assigned coast between 34 degrees and 41 degrees north latitude, and the Virginia Company of Plymouth was assigned coast between 38 degrees and 45 degrees north latitude, both including present Pennsylvania. Colonies of the two companies were to be at least 100 miles apart, even in area of overlapping grants. (Paullin, pl. 42; Swindler, 10:17-23; Van Zandt, 92)

2 June 1609

King James I granted a new charter to the Virginia Company of London, redefining its jurisdiction along the coast as 200 miles north and south of Point Comfort (c. 37 degrees north latitude), including islands within 100 miles, and expanding its area westward and northwestward to the Pacific Ocean; covered part of present Pennsylvania. (Paullin, pl. 42; Swindler, 10:24-36; Van Zandt, 92)

12 March 1611 / 1612

King James I granted a new charter to the Virginia Company of London, expanding its jurisdiction to encompass all land between 30 degrees and 41 degrees north latitude (including part of present Pennsylvania), plus offshore islands within 300 leagues, and by implication still extending to the Pacific Ocean. (Swindler, 10:37-45; Van Zandt, 92-93)

3 November 1620

King James I replaced the charter to the Virginia Company of Plymouth with a charter for a Council for New England to establish colonies in a region between 40 degrees and 48 degrees north latitude and extending from the Atlantic to the Pacific Ocean, including part of present Pennsylvania. (Swindler, 5:16-26)

24 May 1624

The Court of the King's Bench revoked the charter of the Virginia Company of London, and Virginia became a royal colony under direct authority of the King and Privy Council. Virginia still claimed jurisdiction as fixed by earlier charters, including part of present Pennsylvania. (Morton, 1:106)

by 3 June 1631

The Dutch established the first European settlement on the west side of Delaware Bay at Zwanendael (now Lewes, Del.). (Munroe, Colonial Delaware, 9-12)

20 June 1632

King Charles I created Maryland from the earlier range of Virginia territory, granting it as a proprietary colony to Cecil Calvert, Lord Baltimore. Territory included all "hitherto uncultivated" land that "lieth under the Fortieth Degree of North Latitude," and was bounded on the south by the south bank of the Potomac River, a line from the river's mouth across Chesapeake Bay to Watkins Point, and thence a line due east across the Delmarva peninsula to the ocean, and on the west by the meridian of the head of the Potomac. Lord Baltimore claimed that this grant extended north to the parallel of 40 degrees north latitude, including part of present Pennsylvania. (Swindler, 4:359; Van Zandt, 81, 85)

March 1638

The New Sweden Company established the first permanent European settlement on the Delaware River at Fort Christina (now Wilmington, Del.). New Sweden claimed and, for the most part, controlled the lower Delaware River region (parts of present Delaware, New Jersey, and Pennsylvania), but settled few colonists there. The Dutch forced the Swedes out on 1655. (McCormick, 12; Munroe, Colonial Delaware, 16; Pomfret, Colonial New Jersey, 4)

15 September 1655

The Dutch captured Fort Casimir (now New Castle, Del.), thereby effectively ending Swedish control of the Delaware River region and annexing it, including all of present Delaware, New Jersey, and eastern Pennsylvania, to New Netherland. (McCormick, 13; Munroe, History of Delaware, 26)

23 April 1662

King Charles II granted Connecticut a charter as a self-governing corporate colony. Boundaries were the southern Massachusetts line on the north (c. 42 degrees north latitude), Narragansett Bay on the east, Long Island Sound on the south (c. 41 degrees north latitude), and the Pacific Ocean ("South Sea") on the west, thereby overlapping present New Jersey, New York, Ohio, Pennsylvania, and other states to the west. (Bowen, 32; Swindler, 2:135-136)

29 August 1664

The Duke of York's forces captured New Amsterdam from the Dutch, swiftly took control of the rest of New Netherland, and renamed the province New York. Territory included present New Jersey, New York, Vermont, and (after Oct. 1664) settlements on the west side of the Delaware River in present Delaware and southeastern Pennsylvania, but without precisely defined boundaries. Some of this territory was south of the parallel of 40 degrees north latitude, in the region covered by the 1632 grant to Maryland. Conquest confirmed by the Treaty of Breda (1667). (Flick, 2:80)

October 1664

The Duke of York's forces captured Ft. Casimir (now New Castle, Del.), thereby completing their conquest of New Netherland and bringing the west side of Delaware Bay (also claimed by Maryland), including present Delaware and Pennsylvania, under the de facto control of the Duke and New York. Conquest confirmed by the Peace of Breda (1667). (Flick, 2:80, Munroe, History of Delaware, 26, 30-31)

21 July 1667

The Peace of Breda, between England and France and the Netherlands, confirmed the English conquest of New York from the Dutch in 1664, including dependent areas along the Delaware River and Bay that covered present Delaware and southeastern Pennsylvania. (Farnham, 7:311, 314; Parry, 10:231)

22 October 1669

Maryland implicitly asserted its claim to an area of present Delaware and Pennsylvania (then controlled by New York) by creating DURHAM (Md., extinct) from SOMERSET (Md.) and non-county area along the Atlantic Coast. (Archives of Md., 5:56-57)

19 June 1672

WORCESTER (Md., original, extinct) created from DURHAM (Md., extinct) and the unnamed coastal county in present Maryland and Delaware. WORCESTER (Md., original) was located in present Delaware and Pennsylvania and never became operational. (Archives of Md., 5:107-110)

August 1673

Dutch forces recaptured the territory of old New Netherland, including present Delaware (also claimed by Maryland), New Jersey, eastern New York, and southeastern Pennsylvania. (Flick, 2:93)

12 September 1673

After completing their re-conquest (August 1673) of old New Netherland, including present Delaware and southeastern Pennsylvania, the Dutch created three county-like courts for settlements along the west side of the Delaware River in area also claimed by Maryland: NEW AMSTEL (now NEW CASTLE, Del.), UPLAND (Del., extinct), and HOARKILL (now SUSSEX, Del.), with no inland limits specified. These courts became the original counties of Delaware. (Docs. of N.Y., 12:507-508; George, Nead, and McCamant, 453-454; Reed, 22)

October 1674

In the fall of 1674, the Dutch returned New York and the Delaware River settlements, including UPLAND (Del., extinct) to the Duke of York in accordance with the Treaty of Westminster (9 February 1673/1674). (Docs. of N.Y., 12:515; George, Nead, and McCamant, 454; Parry, 13:136)

by 6 November 1674

New York declared settlements along the western side of the Delaware River in present Delaware and eastern Pennsylvania to be "dependent" on New York, including NEW AMSTEL (now NEW CASTLE, Del.), UPLAND (Del., extinct), and HOARKILL (now SUSSEX, Del.) This region was also claimed by Maryland. (Docs. of N.Y., 12:515)

by 11 November 1674

In an area of present Delaware, claimed by Maryland but controlled by New York, NEW AMSTEL (Del.) renamed NEW CASTLE (Del.). (Docs. of N.Y., 12:515)

22 September 1676

The Duke of York's laws were extended from New York to the Delaware River region (also claimed by Maryland); UPLAND (Del., extinct) was formally placed under the Duke of York's laws. (Docs. of N.Y., 12:561-563; Reed, 13)

12 November 1678

In the area of present Delaware, claimed by Maryland, but controlled by New York NEW CASTEL (Del.) gained from UPLAND (Del. extinct); included part of present Pennsylvania. (Armstrong, 119, 198)

21 June 1680

In area of present Delaware, claimed by Maryland but controlled by New York, ST. JONES (now KENT, Del.) created from NEW CASTLE (Del.) and HOARKILL (now SUSSEX, Del.); no inland limits specified. (Docs. of N.Y., 12:654, 664, 666-667; Reed, 12)

4 March 1680 / 1681

King Charles II created Pennsylvania from parts of earlier grants to Connecticut and Virginia, granting it as a proprietary colony to William Penn. Territory was to be bounded on the east by the Delaware River and to "extend westwards 5 degrees of longitude. . .from the saide Easterne Bounds," to extend northward to "the beginning of the 3 and fortieth degree" of north latitude, and to be bounded on the south by the arc of a circle, 12 miles in radius and centered in New Castle, Del., from the Delaware River to "the beginning of the fortieth degree" of north latitude. This grant implicitly set the 12-mile circle as the northern limit of the Delaware region, and it covered most of UPLAND (Del., extinct). William Penn claimed the Pennsylvania grant extended south to the parallel of 39 degrees north latitude, in conflict with Lord Baltimore's claim that Maryland's 1632 charter grant extended north to the parallel of 40 degrees north latitude. This dispute was not settled until 1760. (Swindler, 8:243)

by 15 June 1681

In area of present Delaware, claimed by Maryland but controlled by New York, HOARKILL renamed DEALE (now SUSSEX, Del.). (Reed, 13; Turner, 54)

June 1681

UPLAND (Del., extinct) was eliminated when the newly chartered (4 March 1680/1681) proprietary colony of Pennsylvania instituted government for all territory on the west side of the Delaware River from twelve miles north of New Castle, Del. to 42 degrees north latitude. (Armstrong, 196; Swindler, 8:243)

24 August 1682

The Duke of York transferred to William Penn the western Delaware River region (also claimed by Maryland), including DEALE (now SUSSEX, Del.), NEW CASTLE (Del.), and ST. JONES (now KENT, Del.). The northern limit was set by the 12-mile circular boundary around New Castle, Del., and the southern limit at Cape Henlopen, but no limit specified inland from Delaware Bay. NEW CASTLE (Del.) thereby gained the southern remnant of UPLAND (Del., extinct) that had extended south of the circular boundary. (Pa. Arch., 2d ser., 5:739-744)

7 December 1682

William Penn annexed the Delaware River region (present Delaware) to Pennsylvania. The three Delaware courts (termed 'counties" from this date forward) or DEALE (now SUSSEX, Del.), NEW CASTLE (Del.), and ST. JONES (now KENT, Del.) were continued without change, and they became known as the Territories or Lower Counties of Pennsylvania. Maryland did not abandon its claim to the Delaware region but had no control there. (Swindler, 2:191-192)

by 21 December 1682

In area of present Delaware, claimed by Maryland but controlled by Pennsylvania, ST. JONES (Del.) renamed KENT (Del.). (Penn, 2:324)

25 December 1682

In area of present Delaware, claimed by Maryland but controlled by Pennsylvania, DEALE (Del.) renamed SUSSEX (Del.) and gained from KENT (Del.). (Turner, 82)


Pennsylvania created three original counties: BUCKS, CHESTER. and PHILADELPHIA. Territorial limits not specified [not mapped]. (Bronner, 31-35; Hottenstein and Welch, 24, 37, 108; Penn, 2:299)

1 April 1685

Non-County Area 1 created from that part of the colony of Pennsylvania outside the three original counties. (Pennsylvania Provincial Council, 1:73-74)

Boundaries of BUCKS, CHESTER, and PHILADELPHIA defined [no change]. (Pennsylvania Provincial Council, 1:73-74)

13 November 1685

King James II approved the decision of the Committee for Trade and Plantations (7 November 1685) settling the rival claims of Maryland and Pennsylvania to Pennsylvania's Lower Counties (present Delaware) in favor of Pennsylvania. The committee concluded that, because the Maryland charter limited its land grant to "hitherto uncultivated" territory, the 1631 Dutch settlement at Zwanendael (now Lewes)--in their judgment the first European "cultivation" of the area--placed the west side of Delaware Bay outside the grant to Lord Baltimore. The net result of King James' decision was: SUSSEX (Del.) by default implicitly gained territory north of Maryland; WORCESTER (Md., extinct) eliminated ending its overlap with KENT (Del.) and NEW CASTLE (Del.) The boundary line was not fully settled until 1760. (Lunt, 47; Report on the Resurvey, 145; Van Zandt, 81)

28 May 1687

NEW CASTLE (Del.) gained from KENT (Del.). KENT (Del.) gained from SUSSEX (Del.) (Scharf, 2:1030)

by 29 November 1704

KENT (Del.), NEW CASTLE (Del.) and SUSSEX (Del.) eliminated from Pennsylvania when the meeting of a legislative assembly for the Delaware counties signified the separation of Delaware (still known as the Lower Counties) from the rest of Pennslyvania, although the two colonies continued under a common proprietor and governor. (Penn, 4:309; Rodney, 239)

10 May 1729

LANCASTER created from CHESTER and Non-County Area 1. (Pa. Stat., ch. 306, sec. 1/4:131-132)

10 May 1732

Maryland and Pennsylvania agreed that their mutual boundary west of Delaware should be an east-west line running 15 miles south of Philadelphia. This agreement was not a definitive settlement because the two sides could not agree on how to implement it. (Pa. Arch., 2d ser., 16:455)

25 May 1738

In England, the King in Council approved a temporary east-west line between Maryland and Pennsylvania to run 15.25 miles south of Philadelphia east of the Susquehanna River and 14.75 miles south of Philadelphia west of the river [no change]. (Pa. Arch., 2d ser., 16:503)

19 August 1749

YORK created from LANCASTER. (Pa. Stat., ch. 377, sec. 1/5:71, 73)

27 January 1749 / 1750

CUMBERLAND created from LANCASTER and Non-County Area 1. (Pa. Stat., ch. 380, sec. 1/5:87-88)

9 February 1750 / 1751

CUMBERLAND exchanged with YORK. (Pa. Stat., ch. 387, sec. 1/5:106-107)

11 March 1752 / 1752

BERKS created from CUMBERLAND, LANCASTER, PHILADELPHIA, and Non-County Area 1. (Pa. Stat., ch. 392, sec. 1/5:133-134)

NORTHAMPTON created from BUCKS and Non-County Area 1. (Pa. Stat., ch. 393, sec. 1/5:141)

4 July 1760

The proprietors of Maryland and Pennsylvania and the Lower Counties (present Delaware) agreed on the course of their common boundary. Starting at Cape Henlopen, on the Atlantic coast, a line was to run due west halfway across the Delmarva peninsula; from that point the line was to run tangent to the west side of the circular boundary around New Castle and from the tangent point to continue due north until it intersected the parallel of latitude 15 miles due south of the most southern point of the city of Philadelphia; from that point the boundary was to run due west along that parallel to the western limit of Maryland. Surveying problems prevented final implementation until 1769. (Lunt, 56; Report on the Resurvey, 179; Van Zandt, 81-82)

11 January 1769

King George III approved Charles Mason and Jeremiah Dixon's demarcation of the boundary between the Lower Counties (present Delaware) and Maryland, the circular boundary centered on New Castle that divides Delaware and Pennsylvania, and the 1760 east-west boundary between Maryland and Pennsylvania, known as the Mason-Dixon line. (Lunt, 58-61; Report on the Resurvey, 190)

9 March 1771

BEDFORD created from CUMBERLAND. (Pa. Stat., ch. 629, sec. 1/8:46-47)

21 March 1772

BEDFORD gained from CUMBERLAND. (Pa. Stat., ch. 658, sec. 2/8:230)

NORTHUMBERLAND created from BEDFORD, BERKS, CUMBERLAND, LANCASTER, NORTHAMPTON, and Non-County Area 1. (Pa. Stat., ch. 644, sec. 1/8:143-144)

26 February 1773

WESTMORELAND created from BEDFORD. (Pa. Stat., ch. 678, sec. 1/8:314)

11 October 1773

Virginia created West Augusta District, an adjunct of its AUGUSTA County, to provide jurisdiction over the Pittsburgh region in present Pennsylvania. Boundaries not specified at the time (described in detail in 1776 when the district was replaced by three new counties) but obviously meant to cover area around the head of the Ohio River that Virginia claimed was within its 1609 charter limits and west of Pennsylvania's western limit. This extension of Virginia's jurisdiction conflicted with Pennsylvania, which in February had created WESTMORELAND County for the region. At this time Pennsylvania had actual control of the territory. (Abernethy, 94)

12 January 1774

Connecticut created the town of Westmoreland in the northeast corner of present Pennsylvania and put it under the jurisdiction of its LITCHFIELD County, based upon the claim that its charter limits extended west of the Delaware River Boundaries were the Delaware River on the east, a north-south line 15 miles west of Wyoming (now Wilkes-Barre, Pa.) on the west, and on the north and south the limits of Connecticut as defined by its 1662 charter. The Susquehannah Company had first acquired land in this area from the Iroquois in 1754, established a colony of settlers (mostly from Connecticut) in 1771, and set up an independent government in 1773. Pennsylvania insisted on its 1681/1682 charter claim to the area and had established NORTHAMPTON and NORTHUMBERLAND counties in the area, but the settlers held control until 1782. (Cappon, Petchenik, and Long, 17, 92; Conn. Col. Recs., 13:427, 14:218)

April 1774

Virginia took control of Pittsburgh and the surrounding area by force, but permitted Pennsylvania's WESTMORELAND court at Hannastown (30 miles east of Pittsburgh) to continue to function. Against the protests of Pennsylvania, Virginia retained control of the Pittsburgh region until 1780. (Abernethy, 94; Crumrine, "Boundary Controversy," 518; Sosin, 228)

1 August 1774

New York and Pennsylvania agreed to define their boundary as running up the Delaware River to the parallel of 42 degrees north latitude and thence to their western limits. Both colonies were motivated in part by Connecticut's creation (12 January 1774) of the town of Westmoreland in present northeastern Pennsylvania. The point where the 42d parallel intersects the Delaware River was marked in November 1774, the remainder of the line in 1787. (Cappon, Petchenik, and Long, 17; Pratt, 1:241-248)

11 May 1775

LITCHFIELD (Conn.) gained territory in Pennsylvania when Connecticut enlarged town of Westmoreland (present northeastern Pa.), continuing overlap of NORTHAMPTON and NORTHUMBERLAND, and extending to overlap a small part of BEDFORD. (Cappon, Petchenik, and Long, 17, 92; Conn. Col. Recs., 15:13)

14 December 1775

NORTHUMBERLAND's overlap by LITCHFIELD (Conn.) reduced when Connecticut changed the western extent of its town of Westmoreland (present northeastern Pa.) to a straight line running northeastward from a point 15 miles west of the East Branch of the Susquehanna R. on the parallel of 41 degrees north latitude through "the forks of the river Tioga" to the northern limit of the colony. (Cappon, Petchenik, and Long, 17, 92; Conn. Col. Recs., 15:197-198)

29 June 1776

Virginia, in its state constitution, gave up all claims to territory of Maryland, North Carolina, Pennsylvania, and South Carolina, but asserted its claim to all other American territory within the scope of its 1609 charter, including territory north and west of the Ohio River and the territory around Pittsburgh in present Pennsylvania. (Swindler, 10:55)

4 July 1776

Pennsylvania became an independent state. (Declaration of Independence)

10 October 1776

WESTMORELAND (Conn.) created from LITCHFIELD (Conn.) when Connecticut removed its town of Westmoreland (present northeastern Pa.) from LITCHFIELD and made it also "a distinct County," so that thereafter Westmoreland comprised both a town and a county. LITCHFIELD (Conn.) thus eliminated from Pennsylvania, and WESTMORELAND (Conn.) overlapped the Pennsylvania counties of NORTHAMPTON and NORTHUMBERLAND. (Cappon, Petchenik, and Long, 17, 92; Conn. St. Recs., 1:7)

8 November 1776

Virginia created MONONGALIA (W.Va.), OHIO (W.Va.), and YOHOGANIA (extinct) from its West Augusta District, overlapping Pennsylvania's WESTMORELAND County. West Augusta District eliminated. (Cappon, Petchenik, and Long, 93; Hening, 9:262-274)

31 May 1779

MONONGALIA (W. Va.) gained from AUGUSTA (Va.) continuing overlap of WESTMORELAND. (Hening, 10:114)

30 September 1779

BEDFORD gained from CUMBERLAND and NORTHUMBERLAND. (Pa. Stat., ch. 848, sec. 1/9:396-398)

1 October 1780

Pennsylvania regained effective jurisdiction of the Pittsburgh region from Virginia, ending the overlap of WESTMORELAND by MONONGALIA (W.Va.), OHIO (W.Va.), and YOHOGANIA (extinct). The two states had agreed earlier (31 August 1779) that the course of Pennsylvania's western line would be a meridian running north from a point on an extension of the Mason-Dixon line 5 degrees of longitude west of the Delaware R. This line was demarcated in 1784 and 1785 and has not changed since. (Crumrine, "Boundary Controversy," 521-523; Van Zandt, 83)

28 March 1781

WASHINGTON created from WESTMORELAND. (Pa. Stat., ch. 931, sec. 1/10:272-273)

29 October 1782

New York ceded to the United States any claim to territory west of the meridian of the western end of Lake Ontario, thereby defining its western boundary; the Erie Triangle in present Pennsylvania is part of this cession. (Cappon, Petchenik, and Long, 130; Van Zandt, 75)

30 December 1782

A special court of arbitration, established by Congress under the Article of Confederation, Article IX, decided the dispute between Connecticut and Pennsylvania in present northeastern Pennsylvania in favor of Pennsylvania. WESTMORELAND (Conn.) eliminated, ending its overlap with NORTHHAMPTON and NORTHUMBERLAND. Within a few weeks Pennsylvania was exercising full jurisdiction in the area. (Susquehannah Co. Papers, 7:xxxiii, 245)

26 September 1783

FAYETTE created from WESTMORELAND. (Pa. Stat., ch. 1016, sec. 1/11:197)


New Jersey and Pennsylvania agreed on details of their boundary in the Delaware River, including the division of islands [no change]. (Van Zandt, 80)

17 February 1784

FAYETTE gained from WESTMORELAND. (Pa. Stat., ch. 1068, sec. 1/11:234)

9 September 1784

FRANKLIN created from CUMBERLAND. (Pa. Stat., ch. 1107, sec. 1/11:359-360)

10 September 1784

MONTGOMERY created from PHILADELPHIA. (Pa. Stat., ch. 1108, sec. 1/11:364)

4 March 1785

DAUPHIN created from LANCASTER. (Pa. Stat., ch. 1136, sec. 1/11:450)

8 April 1785

NORTHUMBERLAND and WESTMORELAND gained from Non-County Area 1; Non-County Area 1 eliminated. (Pa. Stat., ch. 1164, sec. 15/11:595)

25 September 1786

LUZERNE created from NORTHUMBERLAND. (Pa. Stat., ch. 1244, sec. 1/12:300-301)

27 December 1786

Boundary between LUZERNE and NORTHUMBERLAND redefined [no change]. (Pa. Stat., ch. 1256, sec. 8/12:343)

20 September 1787

HUNTINGDON created from BEDFORD. (Pa. Stat., ch. 1311, sec. 1/12:512-513)

29 September 1787

Boundary between LUZERNE and NORTHUMBERLAND redefined [no change]. (Pa. Stat., ch. 1323, sec. 3/12:588)

24 September 1788

ALLEGHENY created from NORTHUMBERLAND, WASHINGTON, and WESTMORELAND. (Pa. Stat., ch. 1359, sec. 1/13:84-85)

17 September 1789

ALLEGHENY gained from WASHINGTON. (Pa. Stat., ch. 1435, sec. 1/13:319-320)

19 September 1789

MIFFLIN created from CUMBERLAND and NORTHUMBERLAND. (Pa. Stat., ch. 1436, sec. 1/13:321-322)

26 September 1789

DELAWARE created from CHESTER. (Pa. Stat., ch. 1443, sec. 1/13:337-338)

17 March 1790

Boundary between CUMBERLAND and FRANKLIN clarified [no change]. (Pa. Stat., ch. 1498, sec. 1/13:475)

1 April 1791

Boundary between HUNTINGDON and MIFFLIN clarified [no change]. (Pa. Stat., ch. 1544, sec. 1/14:46-47)

3 March 1792

Pennsylvania purchased from the federal government the Erie Triangle, a small area immediately north of Pennsylvania and west of New York, giving Pennsylvania an outlet to Lake Erie. (Van Zandt, 83-84)

29 March 1792

MIFFLIN gained from HUNTINGDON. (Pa. Stat., ch. 1617, sec. 1/14:219-220)

3 April 1792

ALLEGHENY gained all of the Erie Triangle, purchased by Pennsylvania from the federal government on 3 Mar 1792. (Pa. Stat., ch. 1624, sec. 13/14:238-239)

13 April 1795

LYCOMING created from NORTHUMBERLAND. (Pa. Stat., ch. 1834, sec. 1/15:288)

17 April 1795

SOMERSET created from BEDFORD. (Pa. Stat., ch. 1851, sec. 1/15:318)

Boundary between BERKS and NORTHUMBERLAND and LUZERNE and NORTHAMPTON clarified [no change]. (Pa. Stat., ch. 1848, sec. 1/15:312)

9 February 1796

GREENE created from WASHINGTON. (Pa. Stat., ch. 1870, sec. 1/15:380-381)

21 March 1798

WAYNE created from NORTHAMPTON. (Pa. Stat., ch. 1986, sec. 1/16:64)

29 March 1798

FRANKLIN gained from BEDFORD. (Pa. Stat., ch. 1993, sec. 1/16:92)

22 January 1800

ADAMS created from YORK. (Pa. Stat., ch. 2097, sec. 1/16:392)

13 February 1800

CENTRE created from HUNTINGDON, LYCOMING, MIFFLIN, and NORTHUMBERLAND. (Pa. Stat., ch. 2103, sec. 1/16:403)

1 March 1800

SOMERSET gained from BEDFORD. (Pa. Stat., ch. 2111, sec. 1/16:424-425)

12 March 1800

Legislature passed single act creating eight new counties. (Pa. Stat., ch. 2130/16:454-466; for sections and pages on particular counties see following citations)

22 January 1802

WASHINGTON gained from GREENE. (Pa. Stat., ch. 2223, secs. 1-2/17:40-41)

30 March 1803

INDIANA created from LYCOMING and WESTMORELAND; not fully organized, attached to WESTMORELAND. (Pa. Stat., ch. 2374, secs. 1, 3/17:434-435)

7 November 1803

Legislature passed single act organizing four counties. (Pa. Stat., ch. 2391, sec. 1/17:480)

26 March 1804

Legislature passed single act creating six counties. (Pa. Stat., ch. 2478/17:769-775; for sections and pages on particular counties see following citations)

2 April 1804

LYCOMING gained from LUZERNE. (Pa. Stat., ch. 2506, sec. 1/17:846-847)

1 April 1805

WARREN detached from CRAWFORD, attached to VENANGO (but WARREN remained indirectly attached to CRAWFORD, through VENANGO, until 1 September 1805). (Pa. Stat., ch. 2600, sec. 6/17:1033)

1 September 1805

VENANGO fully organized, detached from CRAWFORD. (Pa. Stat., ch. 2600, sec. 1/17:1032)

4 November 1805

ARMSTRONG fully organized, detached from WESTMORELAND. (Pa. Stat., ch. 2553, sec. 1/17:920)

10 March 1806

JEFFERSON detached from WESTMORELAND, attached to INDIANA (but JEFFERSON remained indirectly attached to WESTMORELAND, through INDIANA, until 3 November 1806). (Pa. Stat., ch. 2665, sec. 9/18:123-124)

3 November 1806

INDIANA fully organized, detached from WESTMORELAND. (Pa. Stat., ch. 2665, sec. 1/18:120)

10 April 1807

Middle of Monongahela River fixed as boundary of adjoining counties: ALLEGHENY, FAYETTE, GREENE, WASHINGTON, and WESTMORELAND [no change]. (Pa. Stat., ch. 2863, sec. 1/18:644)

2 November 1807

CAMBRIA fully organized, detached from SOMERSET. (Pa. Stat., ch. 2748, sec. 1/18:339)

28 March 1808

CRAWFORD gained from MERCER. (Pa. Stat., ch. 3008, sec. 1/18:909-910)

LUZERNE gained from NORTHUMBERLAND. (Pa. Stat., ch. 2988, sec. 1/18:887)

21 February 1810

ONTARIO (now BRADFORD) created from LUZERNE and LYCOMING; not fully organized, attached to LUZERNE and LYCOMING. (Pa. Laws 1809-1810, ch. 30, secs. 1, 3/pp. 32-33)

SUSQUEHANNA created from LUZERNE; not fully organized, attached to LUZERNE. (Pa. Laws 1809-1810, ch. 30, secs. 2-3/p. 33)

1 March 1811

SCHUYLKILL created from BERKS and NORTHAMPTON. (Pa. Laws 1810-1811, ch. 54, sec. 1/p. 61)

28 March 1811

LUZERNE gained from ONTARIO (now BRADFORD). (Pa. Laws 1810-1811, ch. 86, sec. 1/pp. 114-115)

6 March 1812

LEHIGH created from NORTHAMPTON. (Pa. Laws 1811-1812, ch. 49, sec. 1/p. 76)

20 March 1812

MIFFLIN gained from NORTHUMBERLAND. (Pa. Laws 1811-1812, ch. 96, sec. 1/p. 141)

24 March 1812

ONTARIO renamed BRADFORD. (Pa. Laws 1811-1812, ch. 109, sec. 1/p. 164)

30 March 1812

HUNTINGDON gained from MIFFLIN. (Pa. Laws 1811-1812, ch. 141, sec. 1/pp. 195-196)

13 October 1812

BRADFORD fully organized, detached from LUZERNE and LYCOMING. SUSQUEHANNA fully organized, detached from LUZERNE. TIOGA fully organized, detached from LYCOMING. (Pa. Laws 1811-1812, ch. 109, sec. 2/p. 164)

16 February 1813

LEBANON created from DAUPHIN and LANCASTER. (Pa. Laws 1812-1813, ch. 52, sec. 1/p. 67)

6 September 1813

COLUMBIA created from NORTHUMBERLAND. (Pa. Laws 1812-1813, ch. 109, secs. 1-2/p. 146)

1 November 1813

NORTHUMBERLAND lost to the creation of UNION. (Pa. Laws 1812-1813, ch. 110, secs. 1-2/p. 150)

1 October 1814

PIKE created from WAYNE. (Pa. Laws 1813-1814, ch. 119, secs. 1-2/p. 205)

21 February 1815

LUZERNE gained from COLUMBIA and LYCOMING. (Pa. Laws 1814-1815, ch. 35, sec. 1/pp. 43-44)

1 May 1815

LYCOMING gained from UNION. (Pa. Laws 1814-1815, ch. 79, sec. 1/p. 119)

NORTHUMBERLAND gained from COLUMBIA. (Pa. Laws 1814-1815, ch. 30, sec. 1/p. 38)

1 September 1815

MCKEAN detached from CENTRE, attached to LYCOMING. (Pa. Laws 1813-1814, ch. 116, sec. 1/p. 201)

1 May 1816

COLUMBIA gained from NORTHUMBERLAND. (Pa. Laws 1815-1816, ch. 9, sec. 1/pp. 6-7)

3 March 1818

SCHUYLKILL gained from COLUMBIA and LUZERNE. (Pa. Laws 1817-1818, ch. 67, sec. 1/pp. 130-131)

1 May 1818

CENTRE gained from LYCOMING. (Pa. Laws 1817-1818, ch. 139, sec. 1/p. 263)

16 March 1819

UNION gained from MIFFLIN. (Pa. Laws 1818-1819, ch. 77, sec. 1/pp. 111-112)

1 May 1819

LYCOMING gained from CENTRE. (Pa. Laws 1818-1819, ch. 118, sec. 1/p. 185)

1 October 1819

WARREN fully organized, detached from VENANGO. (Pa. Laws 1818-1819, ch. 72, secs. 1-2/p. 102)

23 May 1820

CENTRE gained from UNION. (Pa. Laws 1819-1820, ch. 120, sec. 2/pp. 176-177; Linn, 34, 60-61)

1 September 1820

PERRY created from CUMBERLAND. (Pa. Laws 1819-1820, ch. 68, sec. 1/p. 92)

29 March 1821

LEBANON gained from DAUPHIN. (Pa. Laws 1820-1821, ch. 83, sec. 1/p. 145)

29 January 1822

CLEARFIELD fully organized, detached from CENTRE. (Pa. Laws 1821-1822, ch. 7, sec. 1/p. 7)

28 February 1822

CRAWFORD exchanged with VENANGO. (Pa. Laws 1821-1822, ch. 35, sec. 1/pp. 40-41)

18 June 1822

Under authority of the Treaty of Ghent (24 December 1814), commissioners from Great Britain and the United States agreed on the detailed course of the U.S.-Canadian boundary through Lake Erie, in accordance with the Peace Treaty of 1783 [no change]. (Van Zandt, 12-14)

31 March 1823

Boundary between CUMBERLAND and YORK clarified [no change]. (Pa. Laws 1822-1823, ch. 122, sec. 4/p. 193)

1 April 1823

CLEARFIELD gained from LYCOMING. (Pa. Laws 1822-1823, ch. 174, sec. 1/p. 289)

1 September 1826

MCKEAN fully organized, detached from LYCOMING. POTTER attached to MCKEAN. (Pa. Laws 1823-1824, ch. 65, secs. 1, 8/pp. 104, 106)

23 March 1829

Boundary between DAUPHIN and LEBANON clarified [no change]. (Pa. Laws 1828-1829, no. 79, sec. 1/p. 101)

1 October 1830

JEFFERSON fully organized, detached from INDIANA. (Pa. Laws 1829-1830, no. 99, sec. 1/p. 161)

1 May 1831

LYCOMING gained from BRADFORD. (Meginness, 271; Pa. Laws 1828-1829, no. 115, sec. 1/p. 144; Pa. Laws 1830-1831, no. 83, sec. 1/p. 133)

1 September 1831

JUNIATA created from MIFFLIN. (Pa. Laws 1830-1831, no. 67, secs. 1-2/pp. 99-100)

4 May 1832

Boundary between ADAMS and CUMBERLAND redefined [no change]. Boundary between LYCOMING and UNION redefined [no change]. (Pa. Laws 1831-1832, no. 175, secs. 21, 24/pp. 457-458)

15 April 1834

MIFFLIN gained from HUNTINGDON. (Pa. Laws 1833-1834, no. 227, sec. 1/p. 503)

4 April 1835

FRANKLIN gained small area from CUMBERLAND [change too small to display on interactive map; shapefile users see small_changes 1835_pt. for location]. (Pa. Laws 1834-1835, no. 75, sec. 1/pp. 106-107)

1 September 1835

POTTER fully organized, detached from MCKEAN. (Pa. Laws 1832-1833, no. 142, secs. 1, 7/pp. 313-315)

25 May 1836

CENTRE exchanged with LYCOMING. (Pa. Laws 1835-1836, no. 160, sec. 10/p. 511)

1 September 1836

MONROE created from NORTHAMPTON and PIKE. (Pa. Laws 1835-1836, no. 144, secs. 1-2/p. 430)

16 April 1838

ADAMS gained small area from FRANKLIN [change too small to display on interactive map; shapefile users see small_changes 1838_pt. for location]. (Pa. Laws 1837-1838, no. 94, sec. 93/p. 607)

21 June 1839

CLINTON created from CENTRE and LYCOMING. (Pa. Laws 1838-1839, no. 145, sec. 1/p. 362)

19 March 1840

Boundary between ARMSTRONG and WESTMORELAND clarified [no change]. (Pa. Laws 1840, no. 73, sec. 1/p. 167)

14 April 1840

Boundary between CAMBRIA and INDIANA clarified [no change]. (Pa. Laws 1840, no. 144, sec. 67/p. 344)

1 September 1840

CLARION created from ARMSTRONG and VENANGO. (Pa. Laws 1838-1839, no. 27, secs. 1-2/pp. 51-52; Pa. Laws 1840, no. 165, secs. 1-3, 5/pp. 426-428)

28 April 1841

Boundary between FRANKLIN and PERRY redefined [no change]. (Pa. Laws 1841, no. 111, sec. 5/p. 294)

18 April 1843

ELK created from CLEARFIELD, JEFFERSON, and MCKEAN. (Pa. Laws 1843, no. 150, sec. 1/p. 312)

1 May 1843

WYOMING created from LUZERNE. (Pa. Laws 1842, no. 79, sec. 1/p. 222, and no. 104, sec. 1/p. 306)

1 September 1843

CARBON created from MONROE and NORTHAMPTON. (Pa. Laws 1843, no. 41, secs. 1-2/p. 85)

16 April 1845

WARREN gained from MCKEAN. (Pa. Laws 1845, no. 350, sec. 1/p. 541)

27 July 1846

BLAIR created from BEDFORD and HUNTINGDON. (Pa. Laws 1846, no. 55, secs. 1, 13/pp. 64, 66-67)

24 February 1847

Boundary between MCKEAN and WARREN clarified [no change]. (Pa. Laws 1847, no. 104, sec. 5/p. 147)

3 January 1848

SULLIVAN created from LYCOMING. (Pa. Laws 1847, no. 365, secs. 1-2/p. 462)

6 March 1848

Boundary between BERKS and SCHUYLKILL redefined [no change]. (Pa. Laws 1848, no. 89, sec. 1/pp. 98-99)

11 April 1848

FOREST created from JEFFERSON; not fully organized, attached to JEFFERSON. (Pa. Laws 1851, res. 9/pp. 744-745)

29 March 1849

Boundary between BERKS and SCHUYLKILL clarified [no change]. (Pa. Laws 1849, no. 215, sec. 6/p. 261)

1 September 1849

LAWRENCE created from BEAVER and MERCER. (Pa. Laws 1849, no. 366, secs. 1-2/pp. 551-552)

2 April 1850

JEFFERSON gained from FOREST. (Pa. Laws 1850, no. 249, sec. 3/p. 315)

3 May 1850

Boundary between BEDFORD and BLAIR clarified [no change]. (Pa. Laws 1850, no. 394, sec. 3/p. 680)

1 September 1850

FULTON created from BEDFORD. (Pa. Laws 1851, no. 163, secs. 1, 4/p. 217, and no. 495, secs. 1, 3/pp. 805-806)

1 November 1850

MONTOUR created from COLUMBIA. (Pa. Laws 1850, no. 387, secs. 2, 5/pp. 658-659)

15 January 1853

COLUMBIA gained from MONTOUR. (Pa. Laws 1853, no. 3, sec. 2/p. 3)

4 April 1854

MERCER gained from CRAWFORD. (Pa. Laws 1854, no. 255, sec. 1/p. 279)

27 April 1855

Boundary between HUNTINGDON and MIFFLIN clarified [no change]. (Pa. Laws 1855, no. 357, sec. 1/p. 343)

MCKEAN gained from ELK. (Pa. Laws 1855, no. 375, sec. 2/pp. 357-358; Wessman, 15-16)

30 April 1855

INDIANA gained from CAMBRIA and CLEARFIELD. (Pa. Laws 1855, no. 390, sec. 2/p. 373)

1 December 1855

SNYDER created from UNION. (Pa. Laws 1855, no. 555, secs. 1, 7/pp. 537-538)

1 September 1857

FOREST fully organized, detached from JEFFERSON. (Pa. Laws 1857, no. 653, secs. 1-2/pp. 612-613)

2 April 1860

Boundary between COLUMBIA and LUZERNE clarified [no change]. (Pa. Laws 1860, no. 469, sec. 1/pp. 560-561)

12 October 1860

CAMERON created from CLINTON, ELK, MCKEAN, and POTTER. (Pa. Laws 1860, no. 598, secs. 1-2/pp. 697-698)

17 April 1861

UNION gained from LYCOMING. (Pa. Laws 1861, no. 317, sec. 1/p. 335)

1 May 1861

Boundary between COLUMBIA and LUZERNE clarified [no change]. (Pa. Laws 1861, no. 394, sec. 1/p. 424)

5 May 1864

BUTLER gained small area from ARMSTRONG to accommodate local property owner [change too small to display on interactive map; shapefile users see small_changes 1864_pt. for location]. (Pa. Laws 1864, no. 721, sec. 1/p. 826)

16 March 1865

LEBANON gained from BERKS. (Pa. Laws 1865, no. 385, sec. 1/p. 396)

31 October 1866

FOREST gained from VENANGO. (Pa. Laws 1866, no. 1417, sec. 1/pp. 1527-1528, and no. 1418, sec. 3/p. 1530)

2 August 1867

LYCOMING gained from CLINTON. (Lycoming County Road Docket, 1859-1868, vol. 6, p. 530)

21 March 1868

PERRY gained small area from DAUPHIN to accommodate local property owner [change too small to display on interactive map; shapefile users see small_changes 1868_pt. for location]. (History of . . . the Susquehanna and Juniata Valleys, 2:943, 1072; Pa. Laws 1868, no. 375, sec. 1/pp. 413-414)

31 March 1868

CLINTON and UNION gained from LYCOMING. (Pa. Laws 1868, no. 486, secs. 1-2/p. 526)

4 April 1868

ELK gained from CLEARFIELD and JEFFERSON. JEFFERSON gained from CLEARFIELD. (Pa. Laws 1868, no. 611, sec. 1/pp. 651-652)

9 March 1870

ELK gained from FOREST. (Pa. Laws 1870, no. 351, sec. 1/pp. 363-364)

23 February 1871

ELK gained from CLEARFIELD. (Pa. Laws 1871, no. 138, sec. 1/p. 125; Wessman, 15-16)

3 April 1872

Boundary between ELK and FOREST clarified [no change]. (Pa. Laws 1872, no. 821, sec. 1/p. 861)

21 August 1878

LACKAWANNA created from LUZERNE. (Pa. Arch., 4th ser., 9:662-663)

20 December 1887

Boundary between GREENE and WASHINGTON clarified [no discernible change]. ("Report of Commissioners, May 1900." Pa. State Arch., Land Office Recs., no. 66, item 3)

7 September 1900

Boundary between LYCOMING and TIOGA clarified [no discernible change]. ("Commissioners' Report and Map (linen tracing), 1888." Pa. State Arch., Land Office Recs., no. 53, item 27)

30 June 1921

CHESTER exchanged narrow strips of territory with NEW CASTLE (Del.) when Congress ratified agreement between Delaware and Pennsylvania on demarcation of their common boundary. Net result was that CHESTER gained a small sliver of territory, known as the Horn, along the circular line and NEW CASTLE (Del.) gained a small triangular area, known as the Wedge, by the northeast corner of Maryland [not mapped]. (Lunt, 59, 61; Van Zandt, 83)