 It follows that parallel about 30 miles until it intersects the St. Francis River, then follows the river back up to about the 36°30' parallel just west of Campbell, Missouri.Walker served as sheriff of New Madrid County in 1821–22 and later served as a county court judge in Pemiscot County.After the 1851 formation of Pemiscot County from New Madrid County, Walker helped to lay out the town of Caruthersville in 1857 and died there in 1860.