Fire insurance maps are a core resource for documenting the development of neighborhoods over time. Founded in 1867, the Sanborn Map Company was the primary American publisher of fire insurance maps for nearly 100 years. They show lot numbers, square footage of lots, street addresses, which lots have buildings and their shape and materials. They indicate the type of construction, property lines, and the number of stories. They can narrow the date when a building was constructed. They can be used to track demolition, recent construction and alterations. They identify plot numbers necessary to access deed and other civil records.