As part of the 2010 Census geographic product series, the Census Bureau has produced Census Tract Relationship Files. These files show how Census 2000 census tracts relate to 2010 Census census tracts.
The 2010 Census Tract Relationship Files consist of the following:
These files are in comma-delimited ASCII format.
The census tract relationship files consist of one record per each Census 2000 census tract/2010 Census census tract spatial set. A spatial census tract set is defined as the area that is uniquely shared between a Census 2000 census tract and a 2010 Census census tract. The current release includes 53 sets of files: a national file, one for each of the 50 states, the District of Columbia and Puerto Rico.
The substantially changed census tracts files identify those census tracts that exhibit a 2010 Census population change of 2.5-percent or greater–where no single part has at least 97.5% of the total respective tract, and also those tracts where the unique identifiers between Census 2000 and 2010 Census are different–regardless of the population change.