The Piedmont Atlantic Megaregion (PAM) is a neologism created by the Regional Plan Association for an area of the Southeastern United States that includes the Atlanta, Birmingham, Charlotte, Memphis, Nashville, Research Triangle (Raleigh-Durham), and Greensboro-Winston-Salem-High Point 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. Half of the nation's population growth and two-thirds of its economic growth are expected to occur within those regions over the next four decades.