Consider that in 1950, the core cities accounted for nearly 24 percent of the U.S. population; today the share is under 15 percent. Between 2010 and 2020, the suburbs and exurbs of the major metropolitan areas accounted for about 90% of all US metropolitan growth; over that time suburbs and exurbs of the major metropolitan areas gained 2.0 million net domestic migrants, while the urban core counties lost 2.7 million .