Map: Detroit’s Precinct 4 Patrolman’s Beat Map 1918 | DETROITography
▻https://detroitography.com/2017/08/02/map-detroits-precinct-4-patrolmans-beat-map-1918
This example beat map is included in the 1918 Annual Report of the Detroit Police Department.
“Beat Maps: Each patrolman is furnished with a map of his beat upon which is designated all public buildings, all factories, and other important risks, so that he may intelligently patrol his beat.”