Macon (/ˈmeɪkən/), officially Macon–Bibb County, is a consolidated city-county located in the U.S. state of Georgia. Macon lies near the geographic center of the state, approximately 85 miles (137 km) south of Atlanta, hence the city's nickname "The Heart of Georgia". Located near the fall line of the Ocmulgee River, Macon had a 2017 estimated population of 152,663. Macon is the principal city of the Macon metropolitan area, which had an estimated population of 228,914 in 2017. Macon is also the largest city in the Macon–Warner Robins Combined Statistical Area (CSA), a larger trading area with an estimated 420,693 residents in 2017; the CSA abuts the Atlanta metropolitan area just to the north. In a 2012 referendum, voters approved the consolidation of the governments of the City of Macon and Bibb County, and Macon became Georgia's fourth-largest city (just after Columbus). The two governments officially merged on January 1, 2014. Macon is served by three interstate highways: I-16 (connecting the city to Savannah and coastal Georgia), I-75 (connecting the city with Atlanta to the north and Valdosta to the south), and I-475 (a city bypass highway). The city has several institutions of higher education, as well as numerous museums and tourism sites. The area is served by the Middle Georgia Regional Airport and the Herbert Smart Downtown Airport. The mayor of Macon is Robert Reichert, a former Democratic member of the Georgia House of Representatives. Reichert was elected mayor of the newly consolidated city of Macon–Bibb, and he took office on January 1, 2014.