Columbus is a consolidated city-county located on the west-central border of the U.S. state of Georgia. Columbus lies on the Chattahoochee River directly across from Phenix City, Alabama. It is the county seat of Muscogee County, with which it officially merged in 1970; the original merger excluded Bibb City, which joined in 2000 after dissolving its own city charter. Columbus is the second most populous city in Georgia (after Atlanta), and fields the state's fourth-largest metropolitan area. At the 2020 U.S. census, Columbus had a population of 206,922, with 328,883 in the Columbus metropolitan statistical area. The metro area joins the nearby Alabama cities of Auburn and Opelika to form the Columbus–Auburn–Opelika combined statistical area, which had a population of 563,967 in 2020. Columbus lies 100 miles (160 km) southwest of Atlanta. Fort Moore, the United States Army's Maneuver Center of Excellence and a major employer, is located south of the city in southern Muscogee and Chattahoochee counties. Columbus is home to museums and tourism sites, including the National Infantry Museum, dedicated to the U.S. Army's Infantry Branch. It has the longest urban whitewater rafting course in the world constructed on the Chattahoochee River.