"Join John Lewis C-I-O Now" is a reference to the Congress of Industrial Organizations, a federation of labor groups. Proposed by John L. Lewis, president of the United Mine Workers of America, the CIO merged with the American Federation of Labor in 1955 to form the AFl-CIO.
Also to be seen in the photo is the reflection of what may be a customer's automobile.
I have been unable to locate any information about this business, either via a Google search or the Birmingham Yellow Pages for 1920 and 1945 available via the Internet Archive. Perhaps it only operated for a few years; after all, 1937 was deep in the Great Depression.
The photograph was taken by Arthur Rothstein, one of numerous men and women hired by the Resettlement Administration/Farm Security Administration to document rural America during the Depression. Rothstein took photographs in various places in Alabama, but his best known are the ones he took at Gee's Bend in Wilcox County in early 1937. Eleven of Rothstein's photos were used in a New York Times Magazine article about that place published on August 22, 1937. The article was written by John Temple Graves II, a columnist for the Birmingham Age-Herald who during World War II wrote the classic book The Fighting South.
A web site devoted to Rothstein is here. Almost 8000 of his photographs can be found here.
