PLSS Map

http://gislounge.com/what-is-the-public-land-survey-and-why-do-we-still-use-it/

PLSS or Public Land Survey System maps are used to survey land in the United States. It was a way of identifying land before it would be sold. The map above features The United States and the states that were  seperated into sections of land within each state highlighted in different colors. It also features principle meridians and baselines within each state. According to Rachel Quist, "Originally established in 1785 by the Land Ordinance, after the revolutionary war, and further refined in 1851 by the General Land Office (now, the Bureau of Land Management), the Public Land Survey System (PLSS) is still the primary legal definition of most property in the United States.  The PLSS is used in each state, except for the original thirteen states and a few states in the southwest that were originally surveyed based on Spanish land grant boundaries (notably Texas), and is based on a surveyed prime meridian that runs north south and a baseline that runs east west.  There are 37 principal meridians and each is associated with a baseline."