Each state-level entity file is comprised of a record for each unique spatial 1990/2000 census tract area combination within the state. In addition to the 1990 and 2000 census tract codes, each record contains three population figures; the Census 2000 population for the record, the Census 2000 population for the entire 2000 census tract, and the actual or estimated Census 2000 population for the area of the 1990 census tract (not the 1990 population for the 1990 census tract). Also, to identify changes and the proportion of change, the record includes "part" indicators for both the 1990 and 2000 census tracts, and the percent of the Census 2000 population represented for the 1990 and 2000 census tracts represented in that record.
Note: As part of the procedure to provide 2000 population data for 1990 census tracts, the Census Bureau has rounded the Census 2000 tabulation block population data for some of the blocks that are split by 1990 census tract boundaries. This rounding procedure may create individual census tract, county, and/or state population totals that are slightly different from the official Census 2000 population totals. Also, the Census 2000 population for the 1990 census tract and for the record is an estimate for each 1990 census tract that had a 1990 boundary not identical to a Census 2000 census block boundary.
This file type is almost identical to the population-based census tract relationship files, except that these files use street-side mileage, rather than population, as a means to measure relationship.
This file type lists those 1990 census tracts that have exhibited a change of 2.5-percent or more for 2000. It uses the data contained in the population-based census tract relationship file.
Note: The amount of change of 2.5-percent or greater can reflect either a sum of gain or loss of Census 2000 population within a given census tract.
This file type lists all 2000 census tracts that had more than 2.5-percent of their Census 2000 population in a different 1990 census tract.
Note: This file was generated by using the national population-based file to identify all 2000 census tracts that did not have 97.5% of their population in a 1990 census tract with the same number.