The commercial zone of each municipality in the United States, with the exceptions indicated in the note at the end of this section, within which the transportation of passengers or property, in interstate or foreign commerce, when not under a common control, management, or arrangement for a continuous carriage or shipment to or from a point without such zone, is exempt from all provisions of 49 U.S.C. subtitle IV, part B shall be deemed to consist of:

(a) The municipality itself, hereinafter called the base municipality;

(b) All municipalities which are contiguous to the base municipality;

(c) All other municipalities and all unincorporated areas within the United States which are adjacent to the base municipality as follows:

(1) When the base municipality has a population less than 2,500 all unincorporated areas within 3 miles of its corporate limits and all of any other municipality any part of which is within 3 miles of the corporate limits of the base municipality,

(2) When the base municipality has a population of 2,500 but less than 25,000 all unincorporated areas within 4 miles of its corporate limits and all of any other municipality any part of which is within 4 miles of the corporate limits of the base municipality.

(3) When the base municipality has a population of 25,000 but less than 100,000 all unincorporated areas within 6 miles of its corporate limits and all of any other municipality any part of which is within 6 miles of the corporate limits of the base municipality, and

(4) When the base municipality has a population of 100,000 but less than 200,000 all unincorporated areas within 8 miles of its corporate limits and all of any other municipality any part of which is within 8 miles of the corporate limits of the base municipality.

(5) When the base municipality has a population of 200,000 but less than 500,000 all unincorporated areas within 10 miles of its corporate limits and all of any other municipality any part of which is within 10 miles of the corporate limits of the base municipality.

(6) When the base municipality has a population of 500,000 but less than 1 million, all unincorporated areas within 15 miles of its corporate limits and all of any other municipality any part of which is within 15 miles of the corporate limits of the base municipality.

(7) When the base municipality has a population of 1 million or more, all unincorporated areas within 20 miles of its corporate limits and all of any other municipality any part of which is within 20 miles of the corporate limits of the base municipality, and

(d) All municipalities wholly surrounded, or so surrounded except for a water boundary, by the base municipality, by any municipality contiguous thereto, or by any municipality adjacent thereto which is included in the commercial zone of such base municipality under the provisions of paragraph (c) of this section.

[32 FR 20048, Dec. 20, 1967, as amended at 34 FR 9870, June 26, 1969; 34 FR 15482, Oct. 4, 1969; 41 FR 56655, Dec. 29, 1976; 62 FR 15422, Apr. 1, 1997]