"The Chicken Ranch was an illegal but tolerated brothel in the U.S. state of Texas that operated from 1905 until 1973. It was located in Fayette County about 2.5 miles east of downtown La Grange. The business was established by Miss Jessie Williams, and was the basis for the 1978 Broadway musical and later movie The Best Little Whorehouse in Texas.
Now I finally know what ZZ Top was singing about.