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The Public Land Survey System (PLSS) is the surveying method developed and used in the United States to plat, or divide, real property for sale and settling. Also known as the Rectangular Survey System, it was created by the Land Ordinance of 1785 to survey land ceded to the United States by the Treaty of Paris in 1783, following the end of the American Revolution. Beginning with the Seven Ranges, in present-day Ohio, the PLSS has been used as the primary survey method in the United States. Following the passage of the Northwest Ordinance, in 1787, the Surveyor General of the Northwest Territory platted lands in the Northwest Territory. The Surveyor General was later merged with the General Land Office, which later became a part of the U.S Bureau of Land Management, or BLM. Today, the BLM controls the survey, sale, and settling of the new lands, and manages the State Plane Coordinate System.

Originally proposed by Thomas Jefferson to create a nation of "yeoman farmers", the PLSS began shortly after the American Revolutionary War, when the federal government became responsible for large areas of land west of the original thirteen states. The government wished both to distribute land to Revolutionary War soldiers in reward for their services, as well as to sell land as a way of raising money for the nation. Before this could happen, the land needed to be surveyed.

The Land Ordinance of 1785 marks the beginning of the Public Land Survey System. The Continental Congress was deeply in debt following the Declaration of Independence. With little power to tax, the federal government decided to use the sale of the Western Territories to pay off American Revolutionary War debt. The Public Land Survey System has been expanded and slightly modified by Letters of Instruction and Manuals of Instruction, issued by the General Land Office and the Bureau of Land Management and continues in use in most of the states west of Pennsylvania, south to Florida, Alabama, and Mississippi, west to the Pacific Ocean, and north into the Arctic in Alaska.

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