Census Tract Relationship Files
Part of the Census 2000 geographic product series, Census Tract Relationship Files (CTRF) show how 1990 census tracts relate to 2000 census tracts. The files consist of one record for each 1990 census tract/2000 census tract spatial set. A spatial census tract set is defined as the area that is uniquely shared between a 1990 census tract and a 2000 census tract. The CTRF consist of sets of four files for each of the United States and territories. The purpose of these files is to assist users in determining the relationships between 1990 and 2000 census tracts. Two of these files are state-level entity-based census tract relationship files, one providing a measurement of change based on population, the second measures change using street-side mileage. The other two files specifically list census tracts that have experienced significant change (2.5 percent or greater): one from the perspective of 1990 census tracts, the other from the perspective of Census 2000. A set of files for the United States as a whole is also provided.