and the Virgin Islands. The Census Bureau treats each of the other islands mentioned in this chapter as a single geographic unit.)
As noted previously, for purposes of data presentation, the Census Bureau treats Puerto Rico and each Outlying Area as the statistical equivalent of a State. Each entity is divided into first-order subdivisions, similar to counties in most States; however, they are called a variety of terms, none of which is county. (The legal entities called counties in American Samoa represent second-order subdivisions, or minor civil divisions (MCDs); see Chapter 8, “County Subdivisions.”) For the 1990 census, every first-order subdivision is divided into census tracts or block numbering areas (BNAs), which in turn consist of block groups (BGs) and blocks; in the Outlying Areas, only Puerto Rico has census tracts. For previous decennial censuses, except for portions of Puerto Rico that had census blocks identified in recent censuses, the smallest level of geography was the enumeration district (ED). See Chapters 10 and 11 for more information on census tracts/BNAs, BGs, blocks, and EDs.
Figure 7-3. The Basic Geographic Hierarchy
| Puerto Rico/Outlying Areas | |||||||||||||||||||||||
| Places[F7-3 1] | First-Order Subdivisions | ||||||||||||||||||||||
| Census Tracts/ Block Numbering Areas | Minor Civil Divisions (MCDs) | ||||||||||||||||||||||
| Block Groups | Sub-MCDs | ||||||||||||||||||||||
| Blocks | |||||||||||||||||||||||
- ↑ Places include incorporated places and census designated places.
