Calculating the hub On its web pages [12] the Census Bureau provides 2000 census
data for the 65,443 census tracts in the 50 states. Each line of the comma-delimited
text file contains six numbers. The first three numbers identify the state, county, and
census tract. The last three numbers give the population of the tract and the latitude
and longitude in degrees of the population center of the tract. Note that the longitude is
negative because of the convention that east is the positive direction from Greenwich.
Here are a few lines from that file with the commas removed for readability.