Population dynamics are changing all over the nation and you might be surprised to see which major metropolitan areas are on the rise and which are struggling.

Quite frankly, the rapidity with which many major American metros are gaining population is startling. According to recently released U.S. Census data, an impressive 40 percent of U.S. metro areas – of which there are 383 – have posted population increases, considering both domestic and international migrants, topping the national average, which currently hovers around 2.4 percent. Even more impressive, 51 metros have doubled the national rate and 13 managed to triple it.

As quickly as some cities are growing, however, others are having less luck convincing outsiders to relocate and current residents to stay.

Goodbye, Chicago

The Chicagoland areas remains the third largest metro in the U.S. with a population near 10 million. Unfortunately, over the last four years, the city and its surrounding areas have been shedding large portions of its population.

Since 2010, the U.S. Census Bureau reports that Chicagoland has lost approximately 50,000 residents as a result of domestic migration, meaning people are moving but staying in the U.S.  An influx of international migrants, nearly 30,000, has helped to offset the city’s losses, but the overall population is still shrinking.

Maybe It’s Crime, Maybe It’s the Weather

Following the collapse of the housing market and the financial chaos that ensued, Chicagoland lost an estimated 13,000 of its six-figure income households, reported Crain’s Chicago Business.

City officials had hope to begin recouping their losses with the revival of downtown, which promised more and better housing and job prospects. However, the reality of the efforts didn’t match up with the expectations.

While young people fresh out of college have been happy to make the city and its surrounding suburbs their home, Chicagoland’s primary demographic – 30 to 40-year-olds – are still looking beyond the city’s limits for better jobs and housing, Crain’s confirmed.

Herman Brewer, chief of Cook County’s Bureau of Economic Development, told Crain’s that Chicago’s winters, in particular this most recent, may push more people out of the city and into warmer climates.

“There will be a lot of demographic changes after this winter,” he said.

But with the 30- to 40-year-old demographic already leaving the city, perhaps a change is what’s needed to put Chicago’s growth back on the right track. Think of it as a kind of changing of the guard; the older generations of Chicago are making way for the younger, many of whom have already shown an attraction to the city.