Slide 6 of 29
Notes:
Census tracts are small, relatively permanent statistical subdivisions of a county or a statistically equivalent entity. Designed to be relatively homogeneous units with respect to population characteristics, economic status, and living conditions at the time they are established, census tracts generally contain between 1,000 and 8,000 people, with an optimum size of 4,000 people. Census tract boundaries are delineated with the intention of being stable over many decades, so they generally follow relatively permanent visible features. However, they may follow governmental unit boundaries and other invisible features in some instances; the boundary of a state or county is always a census tract boundary.
Census tracts are usually identified by a six-digit number composed of a four-digit basic number and a two-digit numeric suffix; for example, 8001.07. This suffix (.07) indicates that the original tract, tract 8001, was split possibly into seven pieces as a result of population growth. In some maps the census tract may be represented by a single digit number - in those cases the three leading zeroes were omitted for simplification. However, all census tracts have 6 digits (first four and the last two after the decimal).
In 1990 and previous censuses, the Census Bureau created tract-like geographic units, called Block Numbering Areas or BNAs, outside of metropolitan areas. BNAs were discontinued for Census 2000; instead, one or more census tracts were identified for every county and statistically equivalent entity.
Speaker Notes: Census tracts are usually delineated for data presentation purposes by a local group of census data users or the geographic staff of a regional census center in accordance with U.S. Census Bureau guidelines.
