Public Land Survey System
The Washington Meridian—so named because of its passage near Washington, Mississippi—was surveyed and established by deputy surveyor Isaac Briggs in 1803. The Washington Meridian runs north on 91°09’36”W longitude from the principal base line, which is the Mississippi-Louisiana border at 31° north latitude, and it controls all PLSS surveys in southwestern Mississippi, south of the Choctaw Meridian base line and west of the territory controlled by the Saint Stephens Meridian. The Washington Meridian and the Saint Helena Meridian share the same Initial Point on the 31st parallel with the Washington Meridian controlling the territory north of the 31st parallel and the Saint Helena Meridian controlling the territory to the south. Survey townships were run north of the principal base line, while ranges were run both east and west of the Washington meridian.