State Police block off a road and direct traffic in Monroe, Michigan on June 16, 1937, before a Congress of Industrial Organizations (CIO) rally in the town. The CIO had been formed in 1935, by the eight international unions that belonged to the American Federation of labor (AFL), the two later merged in 1955. Monroe is located between Toledo and Detroit and may have been picked as a good location between the two cities, for the labor unions rally held during the depression when there was much union activity and strike action.
Note the Gulf station in the background, with what appear to be two electric gasoline pumps and the nearest being a hand-pumped-visible-glass unit. The Old Motor photo.