The 2010 Census block relationship files are available to the public for download by individual state from the Census Bureau's web site. The relationship files are organized by type of relationship file, i.e. Census 2000 Tabulation Block to 2010 Census Tabulation Block.
Note 1: Tabulation blocks are the blocks used to tabulate and present decennial census data. The 2010 Census collection blocks are the blocks used in operations supporting decennial census data collection.
Note 2: The Census 2000 Tabulation Block to 2010 Census Tabulation Block and 2010 Census Collection Block to 2010 Census Tabulation Block Relationship files were replaced on 3/3/2011. Version 2 of the block relationship files are sorted by the 2010 Census county-census tract-block codes. All files have identical content with the exception of the state of New York. The spatial extent of 2 blocks changed in New York for the 2010 Census resulting in a change in the block relationship files.