46 CFR §7.105

A line drawn from Marquesas Keys, Florida at approximate position latitude 24°47.5′ N, longitude 82°11.2′ W; along the 12-mile line which marks the seaward limits of the territorial sea (as defined in 33 CFR 2.22(a)(1)) to Rio Grande, Texas at approximate position latitude 25°58.6′ N, longitude 96°55.5′ W.