Festus is a city in Jefferson County, Missouri, United States. The population was 11,246 at the 2008 estimated census. Festus and its neighbor Crystal City are often collectively known as the "Twin Cities"; however, they are incorporated separately. Festus is also notable for being the hometown of the Bottle Rockets. It was referenced in the George Jones/Tammy Wynette duet "We're not the Jet Set".