A census block group (BG) is a cluster of census blocks having the same first digit of their four-digit identifying numbers within a census tract. For example, block group 3 (BG 3) within a census tract includes all blocks numbered from 3000 to 3999. BGs generally contain between 600 and 3,000 people, with an optimum size of 1,500 people. Most BGs were delineated by local participants as part of the U.S. Census Bureau's Participant Statistical Areas Program. The U.S. Census Bureau delineated BGs only where a local, state, or tribal government declined to participate or where the U.S. Census Bureau could not identify a potential local or tribal participant.

Key Attribute Fields:

TRACTCE10: Tract Code

BLKGRPCE10: Block Group Code

GEOID10: Code that includeds State, County, Tract, and Block Group

Coordinate System:

• Projection: Lambert Conformal Conic

• XY Coordinate System: NAD 1983 StatePlane Pennsylvania South FIPS 3702 (US Feet)

ArcGIS Online Data: GCS WGS 1984, Decimal DegreesThematic Mapping

Datum: NAD 1983

Units of Measurement: Foot_US

Thematic Mapping:

No particular field for thematic mapping and labeling