Muscogee and Troup counties. It was named after attorney and former Savannah mayor Charles Harris, the son-in-law of Lachlan McIntosh, a Revolutionary War patriot.
The 464 square miles that make up Harris County were part of Creek Indian holdings until the Treaty of Indian Springs in 1825. The first white settlers arrived soon after the forced removal of the Indians to take advantage of the state's land lotteries. The first to arrive were east Georgians, followed by settlers from Pennsylvania, Virginia, and the Carolinas.
Source: New Georgia Encyclopedia
Lee, Meriwether, Muscogee, Talbot and Troup counties in Georgia as well as Chambers County in Alabama.