Sample ballot with racial designations from Louisiana, 1961
In Anderson v. Martin (1964), the Supreme Court concluded that Louisiana's practice of listing the race of each candidate on the ballot was unconstitutional. The opinion is here.
Here's a sample ballot from a Louisiana election from that era, printed in the Lake Charles American-Press, April 7, 1961. Enlarge the image to see "Caucasian" or "Negro" listed beside each candidate.