Form 477 requires broadband providers to submit data on a census-tract basis.  For the original filing or revisions of data for June 30, 2011, or earlier dates, the Form 477 electronic filing system recognizes as valid the combinations of County and Census Tract codes from the Year 2000 Census.

The Census Bureau provides additional guidance about the Year 2000 Census geography:

• Information posted in the Census Bureau guide, Part I, includes year 2000 census tract outline maps for individual counties, in PDF format. Census tract boundaries frequently follow highways or other visible features. (The Census Bureau also provides a listing of County boundary changes after 2000, but before 2010.)