The area of Delaware was part of the original territory of the United States. Included in the grant to William Penn, the Three Lower Counties (Delaware) were annexed as part of the grant establishing the Province of Pennsylvania in 1683. The counties were granted a separate charter providing semi-autonomy in 1701, with generally the same boundary as the present state. In 1776, Delaware declared itself a separate government. Delaware ratified the U.S. Constitution on December 7, 1787; it was the first of the original 13 states to join the Union.

Census data for Delaware are available beginning with the 1790 census.

AMERICAN INDIAN AREAS

Delaware has two state designated tribal statistical areas (SDTSAs).

METROPOLITAN AND MICROPOLITAN STATISTICAL AREAS AND RELATED STATISTICAL AREAS

Delaware has two metropolitan statistical areas, one micropolitan statistical area, one metropolitan division, and one combined statistical area.

COUNTIES

There are three counties in Delaware.  Kent County’s governing body is the levy court.  New Castle and Sussex counties’ are each governed by a county council.

COUNTY SUBDIVISIONS

There are 27 county subdivisions in Delaware. They are all census county divisions (CCDs), which are delineated for statistical purposes, have no legal function, and are not governmental units.  CCDs were first established in Delaware for the 1970 census.  Prior to 1970, the minor civil divisions used in the census included (State) representative districts and hundreds.

PLACES

Delaware has 78 places; 57 incorporated places and 19 census designated places (CDPs).  The incorporated places consist of 10 cities, 44 towns, and 3 villages.

CENSUS TRACTS/BLOCK GROUPS/BLOCKS

Delaware has 218 census tracts, 574 block groups, and 24,115 census blocks.

CONGRESSIONAL DISTRICTS

For the 111^th Congress (January 2009-January 2011), Delaware had one congressional district.  For the 113^th Congress (January 2013-January 2015), Delaware continues to have one congressional district as a result of reapportionment based on the 2010 Census.

SCHOOL DISTRICTS

Delaware has 16 unified school districts.

STATE LEGISLATIVE DISTRICTS

There are 21 state senate districts and 41 state house districts in Delaware. 

URBAN AREAS

Delaware has 14 urban areas; 3 urbanized areas and 11 urban clusters.

ZIP CODE TABULATION AREAS

There are 68 ZIP Code tabulation areas (ZCTAs) in Delaware. 

OTHER INFORMATION OF GENERAL GEOGRAPHIC INTEREST

The northern boundary between the State of Delaware and the Commonwealth of Pennsylvania is known as the Twelve-Mile Circle.  The boundary is a circular arc forming a twelve-mile radius centered at the cupola of the courthouse in the town of New Castle, DE.

1  Source:  U.S. Department of Commerce, Bureau of the Census, Fourteenth Census of the United States, 1923
²  Source:  U.S. Census Bureau, recomputation for historical county level data which relied upon aggregate county level population data with an estimated county centroid resulting in a possible error of up to one mile.
³  Source:  U.S. Department of Commerce, Bureau of the Census, Centers of Population for States and Counties, 1974
⁴  Source:  U.S. Census Bureau, Geography Division, recomputation from archived national block group/enumeration area data resulting in a possible error of up to 1,000 feet.
⁵  Source:  U.S. Census Bureau, Geography Division, recomputation from archived national block group data resulting in a possible error of up to 1,000 feet.
⁶  Source:  U.S. Census Bureau, computation from national block-level data