5 cities attracting 20-somethings in droves

These cities are young at heart, so to speak.

CareerBuilder's recent study looked into the population size of workers ages 22 to 34 in 100 of the most populous cities in the US, from 2001 to 2016. Some urban areas showed a marked increase in the number of younger workers during that 15-year span.

Business Insider spoke with CareerBuilder's chief human resources officer Rosemary Haefner about the results. She notes that, without digging into migration patterns, it's difficult to say whether cities on the list are growing due to young people moving there for work or school or locals aging into the workforce.

"For college towns like Madison, we can assume that a good portion of millennials are coming from across the state and elsewhere to go to college there," she told Business Insider.

However, it is likely that cities on the list attract a younger demographic due to the industries they offer.

"In Madison, there's a high concentration of young workers in software publishing, internet publishing, R&D in the sciences - as well as bars and electronics and appliance stores," Haefner says. "Colorado Springs also shows a big presence of young workers in electronics stories as well as the military."

Here are the cities that have been growing younger the fastest: