A Chicago Transit Authority Green Line train travels West away from downtown Chicago, Thursday, March 23, 2017, in Chicago. Census data shows the Chicago region has lost more residents than any other U.S. metropolitan area, a drop that comes as other Midwestern cities lost population and South and Southwest parts of the country saw gains. (AP Photo/Charles Rex Arbogast)

A Chicago Transit Authority Green Line train travels West away from downtown Chicago, Thursday, March 23, 2017, in Chicago. Census data shows the Chicago region has lost more residents than any other U.S. metropolitan area, a drop that comes as other Midwestern cities lost population and South and Southwest parts of the country saw gains. (AP Photo/Charles Rex Arbogast)

CHICAGO (AP) — The last straw that convinced Chicago native Marissa Marshall it was time to move away was hearing dangerously close gunfire in the rough neighborhood where she found affordable housing.

The 29-year-old, who’s pregnant with her fifth child, relocated about three years ago to a St. Louis suburb where she more easily found jobs and a home where she felt it was safe to send the kids outside.

“I have boys and I didn’t want to raise them in that environment,” Marshall said. “It is easier to go outside of Chicago to get help than stay in Chicago.”

New census data released Thursday shows she’s not alone, with the Chicago area losing more residents than any other U.S. metropolitan area.

The continuing decline coincided with other Midwestern areas, including St. Louis and Cleveland, as the South and Southwest regions of the country saw gains. Two Texas metropolitan areas — Dallas and Houston — reported the biggest numeric increases between July 2015 and July 2016, adding more than 100,000 residents each.

ADVERTISEMENT

There are wide-ranging reasons for the shifts, from families’ concerns about violence and schools to dwindling immigration and fertility rates. But demographers said Thursday’s data also suggest the reanimation of a trend that paused during the recession — of Americans on the move from the Snow Belt to the suburbs of big cities, and to the Sun Belt.

The Chicago area, which includes surrounding communities in Illinois, Indiana and Wisconsin, lost more than 19,500 residents in a year’s time. Cook County, which encompasses Chicago, also led all counties in population drops, with roughly 21,300 fewer residents. Trailing were Michigan’s Wayne County, where Detroit is located, with roughly 7,700 fewer residents; and Baltimore County, which lost more than 6,700 residents.

Meanwhile, Arizona’s Maricopa County had the highest annual population increase, gaining over 81,000 residents, followed by Harris County in Texas and Nevada’s Clark County.

Families leaving Chicago cite the nearly-broke city school system that’s closed over 50 schools since 2013 and a soaring violent crime rate with more than 760 homicides last year, the most in two decades. City demographics experts add in longstanding economic trends like fewer entry level jobs and a sagging industrial core, along with the dismantling of dense neighborhood-based public housing.

Lower immigration rates also have impacted the Chicago region’s dwindling population. Immigration, particularly from Mexico, was the key factor behind most of Chicago’s population growth in the 1990s.

In Illinois, the population decline has been ripe fodder for political battles.

The predominantly Democratic state’s first Republican governor in a decade, Bruce Rauner, has repeatedly blamed historic fiscal mismanagement and a lack of business-friendly laws for the decline, with companies choosing to set up shop in Texas and Florida over Illinois. In return, Democrats in charge have pointed fingers at over two years of state budget gridlock during the Republicans tenure.

ADVERTISEMENT

Chicago Mayor Rahm Emanuel’s office on Thursday called the decline a trend across the Midwest but blamed Illinois politics for exacerbating it and creating fiscal instability.

Demographics experts said one of the drivers behind the population change around the country could be more young people moving than before.

Young people are historically more likely to move around, but the recession put the brakes on the migration. Millenials, roughly 25-to-35-year olds, have moved at lower rates than their predecessors, including Generation-Xers, according to a Pew Research Center analysis last month.

Rolf Pendall of the Urban Institute’s Metropolitan Housing and Communities Policy Center called the trend “a pent-up demand to migrate” by people in their 20s and 30s and a bump in births “in places where families want to move anyway.”

As baby boomers age, U.S. deaths in some regions are expected to rise, which could be contributing to some of the population dips, too.

“In a lot of the colder northern areas — St. Louis, Chicago, but also the northern states — they just don’t have as many young people living there as the rest of the country,” Pendall said.

___

Follow Sophia Tareen on Twitter at https://twitter.com/sophiatareen .

___

Kellman reported from Washington.