Fire insurance maps are an invaluable tool for history research: they give a detailed snapshot of a city’s built environment at a given point in time. And they were made for just about every city, town and village. The Library of Congress has 50,000 fire insurance maps (700,000 individual sheets) in its collection, most of which were produced by the Sanborn Map Company. The Library has just released a resource guide to help researchers navigate its collection, and explain which maps are available (copyright is an issue with more recent maps). Announcement here.

Previously: Fire Insurance Maps Online.