The area of Pennsylvania was part of the original territory of the United States. It was chartered in 1681, although New York did not relinquish its claim to the area until the following year. The southern boundary was resolved with the survey of the Mason and Dixon Line in the 1760s. Connecticut had claims to Pennsylvania territory resolved by award of the Continental Congress in 1782. Pennsylvania ratified the U.S. Constitution on December 12, 1787; it was the second of the original 13 states to join the Union. Pennsylvania assumed generally the same boundary as the present state with the acquisition of the Erie Triangle from New York in 1792. Pennsylvania is one of four states that are legally described as a commonwealth.

Census data for Pennsylvania are available beginning with the 1790 census. Any population that was enumerated in the Erie Triangle was included in Pennsylvania, although this area was not legally part of the state until 1792.

METROPOLITAN AND MICROPOLITAN STATISTICAL AREAS AND RELATED STATISTICAL AREAS

Pennsylvania has 16 metropolitan statistical areas, 21 micropolitan statistical areas, 2 metropolitan divisions, and 8 combined statistical areas.

COUNTIES

There are 67 counties in Pennsylvania.  Philadelphia County and Philadelphia city are governmentally consolidated and function as a municipal government.  All other counties are each governed by a board of county commissioners.

COUNTY SUBDIVISIONS

Pennsylvania has 2,575 county subdivisions known as minor civil divisions (MCDs).  There are 1,546 townships with active functioning governments and 1 township, Cold Spring township in Lebanon County, which is an inactive entity. Each township is governed by an elected board of commissioners or a board of supervisors.  The 1,015 incorporated places are independent of MCDs and serve as 1,027 county subdivisions.  In addition, there is one undefined MCD that consists entirely of water area.

PLACES

Pennsylvania has 1,764 places; 1,015 incorporated places and 749 census designated places (CDPs).  The incorporated places consist of 954 boroughs, 57 cities, 3 municipalities, and 1 town.  MCD and place governments have the same power and functions in Pennsylvania.  Incorporated places in Pennsylvania are independent of county subdivisions.

CENSUS TRACTS/BLOCK GROUPS/BLOCKS

Pennsylvania has 3,218 census tracts, 9,740 block groups, and 421,545 blocks.

CONGRESSIONAL DISTRICTS

For the 111^th Congress (January 2009-January 2011), Pennsylvania had 19 congressional districts.  For the 113^th Congress (January 2013-January 2015), Pennsylvania has 18 congressional districts as a result of reapportionment based on the 2010 Census.

SCHOOL DISTRICTS

Pennsylvania has 501 unified school districts.

STATE LEGISLATIVE DISTRICTS

There are 50 state senate districts and 203 state house districts in Pennsylvania.

URBAN AREAS

Pennsylvania has 137 urban areas; 27 urbanized areas and 110 urban clusters.

ZIP CODE TABULATION AREAS

There are 1,798 ZIP Code tabulation areas (ZCTAs) in Pennsylvania.

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