How were possible the results in Mississippi and South Carolina in 1936?

[If my soul was made of stone]

Prior to the 1950s, South Carolina's voter suppression tactics were the most brutal in the nation. Between direct suppression of Black voter registration, poll taxes, and the lack of a secret ballot (thus allowing voter intimidation), the only bloc that could reliably vote was the white elite that was deeply wedded to the upholding of white supremacy. In the '40s poorer upcountry whites in the textile industry began to support more "progressive" candidates (such as Truman over Thurmond in '48) and Black voter registration increased somewhat, but the loosening of these requirements also allowed the gradual realignment of those most benefited by the prior regime to the Republicans, often via unpledged electors/Southern sectional tickets along the way. Much of the same is true of Mississippi; its initial regime of voter suppression was slightly less brutal, but held on for somewhat longer into the '60s.

[If my soul was made of stone]

Here is an insane fact about SC. From 1900-1948 no republican ever got more than 7% in SC but then in 1952 Eisenhower got 49.3%.

introduction of secret ballot + continuing resentment of national Democrats for their overtures towards civil rights + Thurmond endorsed Ike + Ike's campaign gently courting segregationists