Variations on a Theme: Understanding and Contextualizing Sanborn Fire Insurance Map Typologies

Abstract

Historic Sanborn fire insurance maps of cities in the United States are utilized extensively for comprehending past built environments and evaluating potential environmental risks. While previous research in the spatial humanities has explored diverse contemporary applications for these maps, there has been limited attention devoted to the evolution of Sanborn fire insurance maps over their nearly century-long production history. This study delves into the components of fire insurance maps produced by the Sanborn Map Company, shedding light on their varying formats, scales, and annotations, discussing how they have changed over time. The paper also examines the map correction process and identifies potential alternative sources for accessing fire insurance maps. Additionally, the diverse nature of these maps as source materials is contemplated, emphasizing the valuable insights that can be gained by critically analyzing the construction of Sanborn fire insurance maps. Given the significant reliance of numerous spatial humanities projects on these historic maps, particularly those focused on urban areas, this paper provides important contextualization of this source of geospatial information.