The Piedmont Atlantic Megaregion (PAM) is the name given to an area of the Southeastern United States that includes the Atlanta, Charlotte, Nashville, Birmingham, Upstate South Carolina, Piedmont Triad, and Raleigh-Durham metropolitan areas. The megaregion generally follows the Interstate 85/20 corridor. According to Georgia Tech, PAM represents over 12 percent of the total United States population and covers over 243,000 square miles (630,000 km²) of land.

PAM is just one emergent megalopolis (also known as a megaregion) of eight such regions in the continental United States, so-called because half the nation's population growth and two-thirds of its economic growth is expected to occur within those regions over the next four decades.

Studies by two U.S. universities – Virginia Tech and Georgia Tech – identify The I-85 Corridor in the Southeastern United States area as an "emergent" megalopolis including the primary cities of Birmingham, Atlanta, Greenville, Spartanburg, Charlotte, Winston-Salem, Greensboro, Durham and Raleigh with Charlotte being the largest city and Atlanta being the largest metropolitan area. Both studies refer to the area as the Piedmont megalopolis.