47 CFR §2.106 - Footnote US270
At times not all of the specific regulations that affect the Amateur Radio Service are included in the single listing in 47 CFR §97. http://www.arrl.org/us270
When considering other regulations that affect Part 97, referencing Part 97.303 - Frequency Sharing Requirements", 93.307 -Emission Standards, and 97.313 - Transmitter Power Standards are good places to start.
There has been a lot of work done over the past few years to address Amateur Radio interference to government radio-location activities on the 70-cm band. 97.313 (f) power limitations around certain governmental installations. This Part 97 rule references US270 - which is the authority for limiting Amateur output power between 420 and 450 MHz.. Footnote US270 is found in 47 CFR §2.106 which can be downloaded here.
The full text of Footnote US270 reads:
47 CFR §2.106 Table of Frequency Allocations.
United States (US) Footnotes
(These footnotes, each consisting of the letters “US” followed by one or more digits, denote stipulations applicable to both Federal and non-Federal operations and thus appear in both the Federal Table and the non-Federal Table.)
US270 In the band 420-450 MHz, the following provisions shall apply to the amateur service:
(a) The peak envelope power of an amateur station shall not exceed 50 watts in the following areas, unless expressly authorized by the FCC after mutual agreement, on a case-by-case basis, between the District Director of the applicable field office and the military area frequency coordinator at the applicable military base. For areas (5) through (7), the appropriate military coordinator is located at Peterson AFB, CO.
(1) Arizona, Florida and New Mexico.
(2) Within those portions of California and Nevada that are south of latitude 37°0' N.
(3) Within that portion of Texas that is west of longitude 104° W.
(4) Within 322 km of Eglin AFB, FL (30°30' N, 86°30' W); Patrick AFB, FL (28°21' N, 80°43' W); and the Pacific Missile Test Center, Point Mugu, CA (34°09' N, 119°11' W).
(5) Within 240 km of Beale AFB, CA (39°08' N, 121°26' W).
(6) Within 200 km of Goodfellow AFB, TX (31°25' N, 100°24' W) and Warner Robins AFB, GA (32°38' N, 83°35' W).
(7) Within 160 km of Clear AFS, AK (64°17' N, 149°10' W); Concrete, ND (48°43' N, 97°54' W); and Otis AFB, MA (41°45' N, 70°32' W).
(b) In the sub-band 420-430 MHz, the amateur service is not allocated north of Line A (def. §2.1).