Hearing on H.R. 7431, Vol. 3
This map was presented by the DC Chief of Police during hearings relating to the March on Washington before the Senate Committee on Appropriations, Subcommittee on District of Columbia. The map shows the division of the area surrounding the March grounds into four zones to aid communications and allocations of police manpower.
Hearing on H.R. 7431, Vol. 3, p. 2422-3; Committee on Appropriations, Subcommittee on the District of Columbia; Records of the U.S. Senate, Record Group 46; National Archives Building, Washington, DC.