Fire Insurance Map of the Semet-Solvay Co. & Semet Groups Chemical Works, Detroit, Michigan, February 21, 1925

Fire insurance maps provided information to insurance companies about potential risks to homes, businesses, and factories. These maps -- with their easily identifiable symbols and color-coding -- depicted structural features, types of construction, and locations of fire hazards. Armed with this information, insurance underwriters could propose reasonable rates and offer protection against possible catastrophic financial loss in the event of a fire.