There were only four towns in Bergen County with lower median ages than the national and state average of 37.6, according to figures from 2005 to 2009 compared to those from 2011 to 2015.
Towns in Bergen County are comprised of people who have higher median ages than fellow New Jerseyans, the most recent Census data shows.
There were only four towns in Bergen County with lower median ages than the national and state average of 37.6, according to figures from 2005 to 2009, compared to those from 2011 to 2015.
Overall, the county's median age was 41.5 and was a .8 percent increase from that same period, or from pre-to post-recession.
The lowest median age in the state's most populous county was 35.4 in Garfield. There was no change in median ages from pre-to post-recession in the town, according to the data.
Philip Dolce, a history professor at Bergen Community College and director of the school's suburban studies program, said millennials prefer living in urban areas, where they can easily work and socialize, and their preferences are shifting the demographics of New Jersey's suburbs.
Millennials, considered those who are now between the ages of 18 and 34, are choosing city life and opting out of big purchases, such as buying a car or a picket-fenced home, Dolce said.
"Suburbia is changing and it's changing rapidly," Dolce said.
He noted that some towns have tried to "revitalize" their downtowns by constructing apartment complexes and building restaurants to attract a younger crowd.
Hackensack, for example, has long-planned projects for its downtown area.
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In Garfield, where median ages are the lowest, the population increased (by about 8 percent), but household median incomes decreased (by about 19 percent).
The same is true for the county overall. In Bergen County, the population increased more than the state, but less than the country and median incomes decreased, but not by as much as in New Jersey or the country.
Home values decreased in the county, not as much as in the rest of the state, but more than the country as a whole.
Dolce cautioned towns to not forget the residents who aren't leaving for a higher paced urban living: senior citizens.
"They have life experience, business experience. We never ask what they can contribute," he said. "That doesn't develop community."
Sara Jerde may be reached at sjerde@njadvancemedia.com. Follow her on Twitter @SaraJerde.