Oldham County is a county located in the north central part of the U.S. state and commonwealth of Kentucky. As of the 2020 census, the population was 67,607. Its county seat is La Grange. The county is named for Colonel William Oldham. Oldham County is part of the Louisville/Jefferson County, KY–IN Metropolitan Statistical Area. Oldham County is the wealthiest county in Kentucky and 47th-wealthiest county in the U.S. and ranks as the most educated county in Kentucky.