Richard Florida:

America’s largest metro areas, which are currently gaining population at impressive rates, are driving much of the population growth across the nation. But that growth is the result of two very different migrations–one coming from the location choices of Americans themselves, the other shaped by where new immigrants from outside the US are heading.
 Working closely with demographer and Martin Prosperity Institute (MPI) colleague Karen King, I decided to take a closer look at newly released data from the US Census Bureau, which breaks out metro population growth according to its various components. We looked at domestic migration; international migration; and net migration for 2012 to 2013. MPI’s Zara Matheson mapped the patterns.
 While many metro areas are attracting a net-inflow of migrants from other parts of the country, in several of the largest metros–New York, Los Angeles, and Miami, especially–there is actually a net outflow of Americans to the rest of the country. Immigration is driving population growth in these places. Sunbelt metros like Houston, Dallas, and Phoenix, and knowledge hubs like Austin, Seattle, San Francisco, and Washington, DC are gaining much more from domestic migration.