33 C.F.R. § 3.40-60
Sector Lower Mississippi River's office is located in Memphis, TN. Subject to the overriding provisions of § 3.40-5 , the boundaries of Sector Lower Mississippi River's Marine Inspection Zone and Captain of the Port Zone include all of Arkansas and all of Oklahoma with the exception of the Red River and Lake Texoma; in Missouri: Dunklin and Pemiscot Counties. In Tennessee: Dyer, Lauderdale, Obion, Tipton, and Shelby Counties, and all portions of Lake County with the exception of the area north and west of a line drawn from Mississippi River at latitude 36°20'00 N and longitude 89°32'30" W due east to Highway 78 thence northeast along Highway 78 to the Kentucky-Tennessee state line; in Mississippi: Desoto, Tunica, Coahoma, Bolivar, Washington, Humphreys, Holmes, Sharkey, Yazoo, Issaquena, Warren, Claiborne, Jefferson, Adams, and Wilkinson Counties; in Louisiana, all the areas north of a line drawn from the east bank of the Mississippi River at the Louisiana-Mississippi border, thence south along the east bank to mile 303.0, thence west to the west bank at mile 303.0, thence north to the southern boundary of the Old River Lock Structure, thence west along the southern bank of the Lower Old River, to the intersection with the Red River, thence west and northwest along the southern bank of the Red River to the northern-most boundary of Red River Parish, thence west along the northern boundary of Red River Parish and DeSoto Parish to the Texas-Louisiana Border, including Lasalle, Caldwell, Caddo, Bossier, Webster, Claiborne, Union, Morehouse, West Carroll, East Carroll, Madison, Richland, Ouachita, Lincoln, Jackson, Bienville, Winn, Grant, Franklin, Tensas, Catahoula, and Concordia Parishes; those parts of Avoyelles, Natchitoches, Rapides, and Red River Parishes north of the Red River, and that part of West Feliciana Parish north of the Lower Old River; that part of the Lower Mississippi River below mile 869.0 and above mile 303; and all of the Red River below the Arkansas-Oklahoma border.
33 C.F.R. §3.40-60