Arguably the most significant legacy of the Civil War at that time was the issue of racial equality. At the turn of the century, millions of African Americans in the South were systematically denied basic civil rights, such as the right to vote and the right to stand for public office. The Civil War had been fought to end slavery, yet despite the Union victory and the subsequent passing of the Fourteenth Amendment, Southern states had been allowed to construct an entire legal edifice of discrimination that effectively reintroduced slavery by the back door, in substance if not in form.
The so-called Jim Crow laws were buttressed by political indifference at the federal government level. To put it bluntly, there simply weren't many votes for civil rights from either party. In addition, the US Supreme Court refused to dismantle Jim Crow, ruling in the notorious case of Plessy v. Ferguson (1896) that racially segregated facilities were constitutional so long as they were "separate but equal."