Sanborn maps are special maps produced to assist insurance companies in determining risk and setting rates.  The maps show the location, occupancy, and construction of commercial buildings within a town.

Reading the maps generally require some mastery of the key.  For an example the Bank Building is 2 story with a composition roof with a 12 inch fire wall.  Each interior floor has a 12 foot ceiling and the building is 26 foot wide (see 1926 map).

1894 Tracy City

1901 Tracy City

1907 Tracy City

1917 Tracy City

1926 Tracy City

Sanborn Key