The Louisiana principal meridian—first surveyed in 1807—runs through the middle of the state, and is the basis for all public land surveys in Louisiana west of the Mississippi River. The meridian lies in 92°24’15”W longitude, and extends from the Gulf of Mexico to the north boundary of Louisiana. The base line is approximately the 31st parallel of latitude. The initial point is located near the town of Lecompte. There is no commemorative monument marking this point, but a federal surveyor did mark the point in 1937. Ranges were run both east and west of the Louisiana meridian, and survey townships were run both north and south of the Louisiana base line. There were many French and otherwise private land claims in Louisiana that were not surveyed using units of the PLSS, but rather surveyed according to French traditions creating long, rectangular lots, typically adjacent to waterways, measured in arpents rather than chains.
