The revised Form 477 requires broadband providers to submit data on a census-tract basis.  The Federal Financial Institutions Examination Council Geocoding System provides a useful resource for matching individual service-location addresses to census tracts.

The Census Bureau provides guidance on identifying census tracts and locating resources for matching service-location addresses with their census tracts.

• Information posted in the Census Bureau guide, Part I, includes, for example: year 2000 census tract numbers (by county) in two separate text files, for Alabama through Montana and Nebraska through Wyoming and Puerto Rico, and year 2000 census tract outline maps for individual counties, in PDF format. (The Census Bureau also provides a listing of County boundary changes after 2000.)
  
  
• In this list of vendors, item 8, the Census Bureau has listed some of the many commercial vendors of Geocoding, Address Matching software or services.

The entire area and population of a county are covered by census tracts. Census tracts within a county are identified by a four-digit basic number between 0001 and 9999, and may have a two-digit numeric suffix ranging from .01 to .98; for example, 6059.02. The decimal point separating the four-digit basic tract number from the two-digit suffix is shown in Census Bureau printed reports and maps. However, in computer-readable files prepared by the Census Bureau, the decimal point is implied, and does not appear. See the Census 2000 Geographic Definitions for more information.

A census tract number may not be used more than once in a single county, but it may be used again in a different county in the same state or in a county in a different state. Therefore, a particular census tract within the nation can be fully identified by: its state, its county, and its census tract number. Alternatively, the particular census tract can be identified by an 11-digit number consisting of a 2-digit code for the state, a 3-digit code for the county (either of which may include one or more “leading” zeros), and 6 digits for the census tract (including any leading zeros, and also two “trailing” zeros in the many cases in which the basic census tract number has no suffix). For example, the Office of the California Secretary of State, located at 1500 11th St, Sacramento, CA 95814, can be fully identified by the 11-digit number 06067000900, in which:

   06 - identifies California,
        067 - identifies Sacramento County within California, and
              000900 - identifies census tract 9 within Sacramento County.

The 2-digit state code and 3-digit county code are Federal Information Processing Standards (FIPS) codes. See the FIPS 6-4 County Lookup in which the “Search by county name” function will provide both state and county FIPS codes.