Slide 5 of 29
Notes:
A statistical subdivision of a census tract (or, prior to Census 2000, a block numbering area), a block group consists of a cluster of census blocks having the same first digit of their identifying numbers within that tract.
For example, for Census 2000, BG 3 within a census tract includes all blocks numbered from 3000 to 3999. (A few BGs consist of a single block.) BGs generally contain between 300 and 3,000 people, with an optimum size of 1,500 people.
The BG is the lowest-level geographic entity for which the U.S. Census Bureau tabulates sample data from a decennial census.
