From the WSJ:
Large U.S. cities lost tens of thousands of millennial and younger Gen X residents last year, according to Census figures released Thursday that offer fresh signs of cooling urban growth.
Cities with more than a half million people collectively lost almost 27,000 residents age 25 to 39 in 2018, according to a Wall Street Journal analysis of the figures. It was the fourth consecutive year that big cities saw this population of young adults shrink. New York, Chicago, Houston, San Francisco, Las Vegas, Washington and Portland, Ore., were among those that lost large numbers of residents in this age group.
The drop in young urban residents last year was smaller than in 2017, when big cities lost nearly 54,000 residents in this age group. But the sustained declines signal a sharp reversal from the beginning of the decade, when young adults flooded into cities and helped lead an urban revival.
Separate Census figures show the majority of people in these age groups who leave cities move to nearby suburbs or the suburbs of other metro areas.
City officials say that high housing costs and poor schools are main reasons that people are leaving. Although millennials—the cohort born between 1981 and 1996—are marrying and having children at lower rates than previous generations, those who do are following in their footsteps and often settling down in suburbs.