This collection contains Sanborn fire insurance maps of cities across Colorado. The CU-Boulder Map Library has the most complete collection of Sanborn maps for Colorado outside of the Library of Congress.
A subset of this collection has been digitized and can be browsed in the CU Digital Library. The digital collection contains 346 maps (on 2,385 sheets) of 79 principal cities in 52 counties covering the years 1883-1922.
The Sanborn maps owned by the University of Colorado Boulder are all in the Libraries' catalog. You can search for a specific city ("[city name] sanborn maps"). The print collection contains maps for approximately 560 cities, beginning in 1883 and ending in 1937.
Sanborn maps may be viewed by appointment only. They don’t circulate and may not be photocopied. Digital photos are permitted.
D.A. Sanborn's Company was founded in 1867 in New York City. These maps were originally designed for fire insurance underwriters to determine the risk involved in insuring individual properties. They show the size, shape, and construction of buildings as well as street names, property boundaries, and building use. Currently, they may be used for a variety of purposes, including environmental site assessment, architecture, urban history, and genealogy.
Other libraries' holdings of Sanborn maps for Colorado and other states may be found on UC Berkeley's Union List of Sanborn and Other Fire Insurance Maps.
More information about the history and use of Sanborn Fire Insurance Maps can be found at the Library of Congress website.
The Library of Congress also hosts the Sanborn Fire Insurance Maps Online Checklist, which includes a searchable database and state-by-state index of the Sanborn maps held by the Library of Congress as well as other information about the maps.