FMSCA Regulation 372.243
372.243 Controlling distances and population data.
In the application of 372.241:
(a) Air-line distances or mileages about corporate limits of municipalities shall be used.
(b) The population of any municipality shall be deemed to be the highest figure shown for that municipality in any decennial census since (and including) the 1940 decennial census.
(c) Contraction of municipal boundaries will not alter the size of commercial zones.
