Raleigh is located in the northeast central region of North Carolina, where the Piedmont and Atlantic Coastal Plain regions meet. This area is known as the "fall line" because it marks the elevation inland at which waterfalls begin to appear in creeks and rivers. As a result, most of Raleigh features gently rolling hills that slope eastward toward the state's flat coastal plain. Its central Piedmont location situates Raleigh about two hours west of Atlantic Beach, North Carolina, by car and four hours east of the Great Smoky Mountains. The city is 155 miles (249 km) south of Richmond, Virginia, 263 miles (423 km) south of Washington, D.C., and 150 miles (240 km) northeast of Charlotte, North Carolina.