Library of Congress - Sanborn Maps
The Library of Congress has placed online nearly 25,000 Sanborn Fire Insurance Maps, which depict the structure and use of buildings in U.S. cities and towns. Maps will be added monthly until 2020, for a total of approximately 500,000. The online collection now features maps published prior to 1900. The states available include Arizona, Arkansas, Colorado, Delaware, Iowa, Kentucky, Louisiana, Michigan, Nebraska, Nevada, North Dakota, South Dakota, Vermont, Wisconsin and Wyoming. Alaska is also online, with maps published through the early 1960s. By 2020, all the states will be online, showing maps from the late 1880s through the early 1960s.