The lynching that "inspired" Allan/Meerapol took place in Indiana, the Midwest, not the South, yet he relocated it in order to juxtapose the symbols of Southern aristocracy with images death.

There is a certain disengenuity here, because, if you look at the famous picture of the Marion lynching, you will observe that the mob consists mostly the sort of Midwestern farmer/factory worker-type "proletarians" (who the Communists liked to champion as the salt of the earth), rather than unreconstructed Confederate Aristocrats--

It seems more like a veiled political tract that tows the party line about racism, rather than a plea for justice or a rallying cry for freedom--