The lot and block survey system is a method used in the United States and Canada to locate and identify land, particularly for lots in densely populated metropolitan areas, suburban areas and exurbs. It is sometimes referred to as the recorded plat survey system or the recorded map survey system. Origins of the system The system is the most recent of the three main survey systems. It began to be widely employed in the United States in the 19th century when cities began to expand into the surrounding farmland. The owners of a large tract of land would create a plat and subdivide the tract into a series of smaller lots to be sold to buyers. This subdivision survey plan would then be recorded with an official government record keeper. The officially recorded map then became the legal description of all the lots in the subdivision. The method became widespread after the post World War II expansion into the suburbs when formerly rural areas became heavily populated and large tracts of rural land were divided into smaller lots. Mechanics The system begins with a large tract of land. This large tract is typically defined by one of the earlier survey systems such as metes and bounds or the Public Land Survey System. A subdivision survey is conducted to divide the original tract into smaller lots and a plat map is created. Usually this subdivision survey employs a metes and bounds system to delineate individual lots within the main tract. Each lot on the plat map is assigned an identifier, usually a number or letter. The plat map is then officially recorded with a government entity such as a city engineer or a recorder of deeds. This plan becomes the legal description of all the lots in the subdivision. A mere reference to the individual lot and the map's place of record is all that is required for a proper legal description. Understanding property descriptions The Lot and Block system is perhaps the simplest of the three main survey systems to understand. For a legal description in the Lot and Block system a description must identify: the individual lot, the block in which the lot is located, if applicable, a reference to a platted subdivision or a phase thereof, a reference to find the cited plat map (i.e., a page and/or volume number), and a description of the map's place of