single data base, all coastlines and inland bodies of water were shown more currently and consistently. With the information in the TIGER data base providing a comprehensive and consistent basis for a new set of area measurement figures, all previous data have been superseded by the 1990 census figures.
- The Census Bureau has provided 1990 area measurement figures for virtually every geographic entity included in its standard data tabulations, down to the census block level; these figures are available in each standard data product that includes a particular class of entity. This is the first time that the Census Bureau has provided measurements for some kinds of geographic entities: the least populous places, census tracts and block numbering areas (BNAs), block groups, census blocks, American Indian reservations, and Alaska Native village statistical areas.
- Inland water includes every body of water that appears in the data base and every stream or similar hydrographic feature recorded as a double-line feature in the data base. As a result of this more accurate and complete inventory of inland water area, the 1990 measurements show an increase in the amount of inland water area when compared to 1980.
- The water areas in the standard data products of the 1990 census reflect all water, whereas the measurements from previous censuses applied only to inland water. As a result, the total area reported for coastal States has increased correspondingly (see section below “The 1990 Census Water Classification Scheme”).
Methodology
In its TIGER data base for the 1990 census, the Census Bureau has calculated measurements for total area, land area, and four types of water areas, for every polygon in the file except census blocks. A census block is identified in the TIGER data base as either all land or all water. This is because tabulation census blocks, that is, entities for which the Census Bureau presents population and housing data, always consist of
Area Measurement/Water Classification15-5
