Union expansion beyond Arkansas brought many locals to Oklahoma, Missouri and Mississippi. The STFU also helped support strikes by fruit canners in California and cane harvesters in Louisiana.

By the 1940s, however, membership in the Southern Tenant Farmers union began to decline. The decline was accelerated by the loss of workers to northern industries gearing up for World War II.

By the 1960s the STFU ceased to exist. Social and political writer Michael Harrington perhaps best expressed its legacy:

“ In one sense the Southern Tenant Farmers Union . . . was defeated, and there is no use trying to walk around the fact. But in that defeat, pressure was generated which left its mark on American history."

Though it slipped quietly out of existence, it provided a lasting legacy of integrated, non-violent protests that would be carried on into the labor and Civil Rights movements of the coming decades