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History
The creation of a plat map marks an important step in the process of incorporating a town or city according to United States law. Because the process of incorporation sometimes occurred at a courthouse, the incorporation papers for many American cities may be stored hundreds of miles away in another state.
For example, to view the original General Land Office plat for the city of San Francisco, California, filed in 1849, one must visit the Museum of the Oregon Territory in Oregon City, Oregon, then the capital of the Oregon Territory and the site of the closest federal land office. This happened because California did not gain statehood until 1850.
