The Land Survey Information System or LSIS is the official government Web site for the distribution of the Public Land Survey System (PLSS) of the United States. The Bureau of Land Management (BLM) cadastral survey program is responsible for the official boundary surveys for all federal agencies in the U.S. that together manage over 700 million acres. The Public Land Survey System also called the Rectangular Survey System is the foundation for many survey-based land information systems.