49 CFR § 372.243
Controlling distances and population data
November 18, 2020
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.
[32 FR 20040, Dec. 20, 1967, as amended at 37 FR 15701, Aug. 4, 1972; 50 FR 10233, Mar. 14, 1985; 62 FR 15422, Apr. 1, 1997]