The 2017 Hillbilly Half Marathon, formerly known as the Franklin Half Marathon. Open to runners and walkers from novice to professional, the Hillbilly Half Marathon and Little Billy 5K celebrates its fifth year in 2017. The USATF certified racecourse is nestled in the pristine backcountry of Williamson County just minutes from downtown Franklin, TN. Over the past five years, the half marathon has attracted up to as many as 1,000 participants each year.