Originally conceived in the late 18th Century, fire insurance maps provided structural and urban environmental information necessary for insurance underwriters. Founded in 1867 in the United States, the Sanborn National Insurance Diagram Bureau systematically produced ascetically appealing, but also efficient, maps nationwide. This New York firm expanded and grew immensely, finally emerging as the Sanborn Map Company in 1902. Eighteen years later the company effectively monopolized the insurance map industry. By World War II surveys of 13,000 towns produced over 700,000 sheets now stored in the Library of Congress. Today, these maps are utilized extensively by architectural historians, environmentalists, genealogists, historians, historic preservationists, and urban historical geographers.