Maryland: Consolidated Chronology of State and County Boundaries

Maryland Atlas of Historical County Boundaries

John H. Long, Editor; Peggy Tuck Sinko, Associate Editor and 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, assigned coast between 34 degrees and 41 degrees north latitude; and the Virginia Company of Plymouth, assigned coast between 38 degrees and 45 degrees north latitude. Colonies of the two companies were to be at least 100 miles apart, even in areas (including present Maryland) of overlapping grants. (Paullin, pl. 42; Swindler, 10:17-23; Van Zandt, 92)

2 June 1609

King James I granted anew 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; this charter covered the area of present Maryland. (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 present Maryland), plus offshore islands within 300 leagues, including Bermuda, and by implication still extending to the Pacific Ocean. (Swindler, 10:37-45; Van Zandt, 92-93)

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 the area of present Maryland. (Morton, 1:106)

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; on the east by the Atlantic Ocean and Delaware Bay (thereby covering all of present Delaware); 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)

by 24 January 1637/1638

ST. MARYS was created as the first county in Maryland. ST. MARYS was meant to serve the entire colony; territorial limits, if any, are unknown, and boundaries are estimated. (Archives of Md., 3:60)

4 October 1638

Virginia formally acknowledged Maryland's existence and implicitly recognized its 1632 boundaries. Virginia renounced any claim to Maryland in 1658 and reiterated that position in its constitution of 1776. (Bozman, 2:72, 586; Van Zandt, 85)

by 2 August 1642

KENT was created from ST. MARYS to serve the east side of Chesapeake Bay; territorial limits were not specified, and boundaries are estimated. (Archives of Md., 3:105)

29 April 1650

ANNE ARUNDEL created from ST. MARYS. The county was centered on the settlement of Providence, but territorial limits were not otherwise specified. (Archives of Md., 1:292)

21 November 1650

CHARLES (original, extinct) created from ST. MARYS; boundaries are estimated. (Archives of Md., 3:259-260)

3 July 1654

CALVERT created from ANNE ARUNDEL and CHARLES (original, extinct); CHARLES (original) eliminated. CALVERT boundaries are estimated. (Archives of Md., 3:308)

20 October 1654

ANNE ARUNDEL renamed PROVIDENCE; CALVERT renamed PATUXENT; ST. MARYS renamed POTOMAC; PROVIDENCE gained from PATUXENT (now CALVERT). (Archives of Md., 1:341, 345, 347)

24 September 1657

KENT boundaries redefined to include Poplar Island [no change]. (Archives of Md., 1:361)

24 March 1657/1658

PATUXENT renamed CALVERT; POTOMAC renamed ST. MARYS; PROVIDENCE renamed ANNE ARUNDEL. (Archives of Md., 1:369)

13 April 1658

CHARLES created from ST. MARYS; territorial limits not specified, and boundaries are estimated. (Archives of Md., 1:381, 3:341)

by 12 January 1659/1660

BALTIMORE created from ANNE ARUNDEL, KENT, and Non-County Area 1. BALTIMORE territorial limits, if any, are unknown and boundaries are estimated. Non-County Area 2 created from Non-County Area 1. (Archives of Md., 1:381)

by 18 February 1661/1662

TALBOT created from KENT and Non-County Area 2; TALBOT territorial limits, if any, are unknown, and boundaries are estimated. (Archives of Md., 1:425)

October 1664

In October 1664, the Duke of York's forces captured Fort 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. The conquest was confirmed in 1667 by the Peace of Breda. (Munroe, History of Delaware, 26, 30-31)

22 August 1666

SOMERSET created from Non-County Area 2. Area included all land between the Nanticoke River and the Atlantic Ocean (including part of southern Delaware), but Maryland did not try to exercise jurisdiction in the eastern part. (Archives of Md., 3:553-555)

25 June 1668

Commissioners from Maryland and Virginia agreed on the demarcation of their boundary across the southern end of the Delmarva Peninsula [no change]. (Archives of Md., 5:44-45)

by 16 February 1668/1669

DORCHESTER created from Non-County Area 2. DORCHESTER territorial limits, if any, are unknown; boundaries were partially defined 6 May 1669. (Archives of Md., 2:155)

6 May 1669

DORCHESTER territorial limits were partially defined [no change]. (Archives of Md., 5:54)

22 October 1669

Maryland implicitly asserted its claim to the area of present Delaware (then controlled by New York) by creating two counties from SOMERSET and non-county area along the Atlantic Coast: DURHAM (extinct), located in present Delaware and Pennsylvania, and an unnamed county in present southern Delaware and Maryland [unnamed county not mapped]. These counties were never operational. (Archives of Md., 5:56-57)

4 June 1671

KENT gained from TALBOT; boundaries are estimated. (Hanson, 221-222)

19 June 1672

DURHAM (extinct) lost all territory to creation of WORCESTER (original, extinct); DURHAM eliminated. (Archives of Md., 5:107-110)

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

12 September 1673

After completing their August 1673 re-conquest of old New Netherland (including present Delaware and southeastern Pennsylvania), the Dutch created three countylike courts for settlements along the west side of the Delaware River in the area also claimed by Maryland: NEW AMSTEL (now NEW CASTLE, Del.), UPLAND (extinct), and HOARKILL (now SUSSEX, Del.). These courts became the original counties of Delaware and all overlapped WORCESTER (original, extinct) [not mapped]. (Docs. of N.Y., 12:507-508; George, Nead, and McCamant, 453-454; Reed, 22)

by 6 June 1674

CECIL created from BALTIMORE and KENT. (Archives of Md., 15:38-39)

ANNE ARUNDEL gained from CALVERT and Non-County Area 1. Boundary between ANNE ARUNDEL and BALTIMORE was redefined [no change]. (Archives of Md., 15:39)

19 June 1674

KENT gained from CECIL, boundary is estimated. (Archives of Md., 15:41)

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 to be bounded on the southeast 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 northern limit of Maryland and the Delaware River region. 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)

24 August 1682

William Penn annexed the Delaware River region to Pennsylvania, and the area 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. (Pa. Archives, 2d ser., 5:739-744)

4 October 1684

Boundary between DORCHESTER and SOMERSET was clarified [no change]. (Archives of Md., 17:286-287)

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, now Delaware. Where the boundary should run was not settled until 1760. SOMERSET implicitly regained area along the Atlantic coast between Delaware and Virginia, and lost to SUSSEX (Del.) in present Delaware. WORCESTER (original) eliminated. (Lunt, 47; Report on the Resurvey, 145; Van Zandt, 81)

23 April 1696

PRINCE GEORGES created from CALVERT, CHARLES, and Non-County Area 1. CHARLES and ST. MARYS gained from CALVERT. KENT exchanged with TALBOT. (Archives of Md., 19:213, 214)

3 April 1698

ANNE ARUNDEL exchanged with BALTIMORE. (Archives of Md., 22:147)

1 May 1707

QUEEN ANNES created from DORCHESTER, KENT, and TALBOT. KENT gained from CECIL. (Archives of Md., 26:621)

31 May 1727

ANNE ARUNDEL gained from BALTIMORE. (Archives of Md., 36:595)

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. Archives, 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. (Pa. Archives, 2d ser., 16:503)

10 December 1742

WORCESTER created from SOMERSET. (Archives of Md., 42:428, 657)

17 October 1746

Royal commissioners placed a marker, the Fairfax Stone, at the headspring of the north branch of the Potomac River to identify it as the source of the Potomac, and, therefore, the western limit of Maryland. (Paullin, 78; Van Zandt, 88, 94)

10 December 1748

CHARLES gained from PRINCE GEORGES. FREDERICK created from PRINCE GEORGES and Non-County Area 1. (Archives of Md., 46:141-142)

2 June 1750

FREDERICK gained from BALTIMORE. Boundaries of DORCHESTER, SOMERSET and WORCESTER clarified [no change]. (Archives of Md., 46:468)

4 July 1760

The proprietors of Maryland and Pennsylvania and the Lower Counties (now Delaware) agreed on the course of their common boundary. Starting at Cape Henlopen, the southeast corner of the Lower Counties, 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 1760 boundary between the Lower Counties (now Delaware) and Maryland, and the east-west line between Maryland and Pennsylvania. Except for later surveyors' adjustments, these lines have not changed. (Report on the Resurvey, 190; Lunt, 58-61)

2 March 1774

HARFORD created from BALTIMORE. (Archives of Md., 64:198)

15 March 1774

CAROLINE created from DORCHESTER and QUEEN ANNES. (Archives of Md., 64:209)

4 July 1776

Maryland became an independent state. (Declaration of Independence)

2 October 1776

MONTGOMERY and WASHINGTON created from FREDERICK. (Md., Laws Since 1763, "Proceedings of Convention," 6 Sep. 1776)

28 March 1785

Commissioners from Maryland and Virginia, concerned with trade and navigation between their states in Chesapeake Bay, defined their mutual boundary across the Bay as running from Smith's Point at the mouth of the Potomac River to "Watkins's Point, near the mouth of Pocomoke River" on the Eastern Shore. This first attempt to specify details of the overwater boundary proved unsatisfactory and was replaced by an informal arrangement in 1868. (Hening, 12:50; Paullin, 85)


Francis Deakins demarcated a line running north from the Fairfax Stone at the headspring of the Potomac River to Pennsylvania as the western limit of bounty lands he was surveying for Maryland. The Deakins Line has been observed ever since as the western limit of Maryland. (Paullin, 78; Van Zandt, 88)

29 December 1789

ALLEGANY created from WASHINGTON. (Md. Laws 1789, Nov. sess., ch. 19)

30 March 1791

The United States created an unnamed district from land ceded by Maryland and Virginia to be the seat of national government. The district was a square with each corner at a point of the compass and each side ten miles long. MONTGOMERY and PRINCE GEORGES continued county functions of Maryland in the ceded area. (Richardson, 1:102; Van Zandt, 90)

22 December 1792

Boundary between CAROLINE and DORCHESTER was adjusted [not mapped]. (Md. Laws 1792, Nov. sess., ch. 19)

27 February 1801

MONTGOMERY and PRINCE GEORGES lost to creation of WASHINGTON (D.C., extinct) when the federal government established a circuit court for the seat of national government (now called the District of Columbia) and created two counties to administer judicial and administrative functions; MONTGOMERY eliminated from the District of Columbia. (U.S. Stat., vol. 2, ch. 15 [1801]/pp. 103-108; Bryan, 1:400-401)

24 February 1824

CALVERT gained from ANNE ARUNDEL. (Md. Laws 1823, ch. 183, sec. 1/pp. 125-126)

18 February 1825

Boundary between ANNE ARUNDEL and CALVERT was clarified [no change]. (Md. Laws 1824, ch. 193/p. 147)

17 February 1826

Boundary between CAROLINE and DORCHESTER was adjusted to accommodate local property owner [not mapped]. (Md. Laws 1825, ch. 81, sec. 1/p. 61)

19 January 1836

CARROLL created from BALTIMORE and FREDERICK. (Md. Laws 1835, ch. 256, sec. 1; Md. Laws 1836, ch. 19)

4 July 1851

HOWARD created from Howard District of ANNE ARUNDEL. (Md. Laws 1838, ch. 22, secs. 1, 4; Swindler, 4:413)

Baltimore City became an independent city, separate from BALTIMORE County. (Swindler, 4:399-410

5 October 1867

WICOMICO created from SOMERSET and WORCESTER. (Swindler, 4:476, 479)

11 December 1868

Oyster inspectors for Maryland and Virginia agreed on a de facto boundary across Chesapeake Bay from the mouth of the Potomac River to the southern tip of Watkins Point on the Eastern Shore. (Paullin, 85)

4 December 1872

GARRETT created from ALLEGANY. As demarcated at the time (and mapped here), the ALLEGANY-GARRETT boundary was run too far west, making GARRETT smaller than it would have been if the legal boundary description was observed. Despite considerable controversy and numerous attempts to move this line to the course originally prescribed, through long observance the original survey line became the effective, legal boundary. (Md. Laws 1872, ch. 212, secs. 1-2/pp. 313-314; Md. Atty. Gen.)

1 April 1878

Boundary between CAROLINE and DORCHESTER was adjusted [not mapped]. (Md. Laws 1878, ch. 393, sec. 2/p. 607)

3 March 1879

SOMERSET lost a small part of Smith's Island to ACCOMACK (Va.) when the United States approved the Maryland-Virginia boundary down the south side of the Potomac River and across Chesapeake Bay [not mapped]. (Paullin, 85; Van Zandt, 87)

11 November 1880

CAROLINE gained part of town of Federalsburg from DORCHESTER, placing the entire town in CAROLINE. (Md. Laws 1880, ch. 208, sec. 1/pp. 332-334; Md. Gov.)

1 June 1888

Baltimore City (Ind. City) gained from BALTIMORE. (Md. Laws 1888, ch. 98, secs. 1-4/pp. 113-117)

21 February 1910

The U.S. Supreme Court confirmed that the Deakins Line of 1788 had become the true western boundary of Maryland through long de facto observance. (Paullin, 79; U.S. Rpts., vol. 217, p. 1)

29 March 1918

Baltimore City (Ind. City) gained from ANNE ARUNDEL and BALTIMORE. (Md. Laws 1918, ch. 82, sec. 1/p. 135)