Columbus is a city in the U.S. state of Georgia and the county seat of Muscogee County, with which it is consolidated. According to the 2013 estimates from the U.S. Census Bureau, Columbus has a population of 202,824 residents, with 316,554 in the greater Columbus-Phenix City metropolitan area. The metro area joins the nearby Alabama cities of Auburn and Opelika to form the Columbus-Auburn-Opelika Combined Statistical Area, which has an estimated population of 501,649. Columbus is directly to the east across the Chattahoochee River from Phenix City, Alabama. Situated at the heart of the Chattahoochee Valley, Columbus is Georgia's second-largest city and fourth-largest metropolitan area.Columbus lies 100 miles (160 km) southwest of Atlanta. Fort Benning, home of the United States Army Infantry School and a major employer, is located south of the city in Chattahoochee County. Columbus is home to museums and tourism sites, including the National Infantry Museum, dedicated to the United States Army's Infantry Branch. It has the longest urban whitewater rafting course in the world constructed on the Chattahoochee River.