Among his many poems are several related in some way to Alabama. As might be expected, they address racial turmoil in the state. The earliest one is "Christ in Alabama", published in the Contempo magazine issue of December 1, 1931. In March of that year two white women accused nine young black men of rape; all had been riding in a train that stopped near Paint Rock in Jackson County. The blacks, dubbed the Scottsboro Boys, were quickly arrested and tried in early April before several all-white juries. The guilty verdicts were appealed and retried for years in the courts despite one of the victims recanting and other exonerating evidence. The case became infamous around the world.
That first poem Hughes wrote about the case can be read below; it imitates the call and response of so much African-American music and its sources in sub-Saharan Africa. "Christ in Alabama" is a brief, blistering cry against this particular injustice and so many others. In the wake of the Scottsboro case 5000 copies of that Contempo issue were printed. A revised version of the poem appeared in 1967. Several commentaries can be found here. Jon Woodson places the poem in context in his essay "Anti-Lynching Poems in the 1930s."
In 1932 Hughes published a twenty page pamphlet titled Scottsboro Limited that included "Christ in Alabama" and three more poems, a verse play and striking illustrations by Prentiss Taylor. You can read some of the poems here; "The Town of Scottsboro" is brief but especially touching.
In that same year Hughes undertook a poetry reading tour of seventeen states that included some in the South. The tour began about the time the Contempo issue appeared. According to Woodson's essay linked above, Hughes read his poetry to the Scottsboro Boys in Kilby Prison.
"For Selma" was included in the collection Ebony Rhythm: An Anthology of Contemporary Negro Verse edited by Beatrice M. Murphy and published in 1947. I'm not sure why he used Selma rather than some other small town, since the voting rights marches did not begin there until 1965. Perhaps he became aware of Selma when he was in the state in 1931. Although he lived in many locations around the country, Hughes did spend 1947 teaching at Atlanta University.
"Birmingham Sunday" is much easier to place, since it explicitly deals with the 16th Street Baptist Church bombing on Sunday, September 15, 1963. That event inspired another African-American poet; see Dudley Randall's "Ballad of Birmingham"
"Alabama Earth" and "Daybreak in Alabama" are different in offering Hughes' hopes that race relations might one day improve "When I get to be a colored composer", even in a place like Alabama. "Alabama Earth" is set "At Booker Washington's grave" which is located on the Tuskegee University campus.
Daybreak in Alabama
Christ in Alabama
Christ is a nigger,
Beaten and black:
Oh, bare your back!
Mary is His mother:
Mammy of the South,
Silence your mouth.
God is His father:
White Master above
Grant Him your love.
Most holy bastard
Of the bleeding mouth,
On the cross
Of the South.
This Decembr 1, 1931, Contempo issue published not only Hughes poem but his essay about the Scottsboro boys case.