A ceremony will be held Friday at 4 p.m. in Meridian on the lawn of the Lauderdale County Courthouse.
McWilliams, who died in 1985, was the sister of Jimmie Rodgers' second wife, Carrie.
Officials say McWilliams wrote or contributed to music and lyrics for 39 of the songs that Rodgers performed or recorded, although she never received full credit for her work.
However, McWilliams became the first woman to sustain a successful career as a country songwriter and was inducted into the Nashville Songwriters Hall of Fame in 1979.