Chatham County is a county in the U.S. state of Georgia, and is on the state's Atlantic coast. The county seat and largest city is Savannah. The county was created on February 5, 1777, and is named after William Pitt, 1st Earl of Chatham.
The U.S. Census Bureau's 2019 population estimate for Chatham County was 289,430 residents which makes it the fifth-most populous county in Georgia, and the most-populous Georgia county outside the Atlanta metropolitan area. The population was counted by the 2010 census at 265,128 in Chatham County. It is part of the Savannah metropolitan area.