This is where you can find most of the city's 6,000 vacant buildings. The crumbling brick homes show what happens to a city that loses two-thirds of its population. Many of the city's black families fled the decaying streets and moved to nearby suburbs — to mostly white communities like Ferguson.

These black families might have escaped the ghetto, but they could not escape racism. The riots that broke out in Ferguson this August reflect the simmering racial tension that has been building in the Rust Belt for a century. St. Louis ranked as one of the nation's top 10 most racially segregated metro areas, according to a 2011 report by researchers at Brown University and Florida State University.

{{ BIZOBJ (video: 5197) }}

St. Louis city and county leaders had been focused on other problems, like how to bring more people and jobs to the region. In 2012, they launched an ambitious plan to make St. Louis the area with the nation's fastest-growing immigrant population by 2020. They created the Mosaic Project, a public-private partnership with nonprofit groups and local business leaders that helps high-skilled immigrants find jobs in the growing biotech industry, among other recruitment efforts.

But not everyone is enthusiastic about these developments. Immigration only seems to benefit the white neighborhoods of south St Louis, says city Alderwoman Sharon Tyus, who represents a predominantly African-American ward with high unemployment and more than 300 empty homes.

"It's frustrating to some people that they spend resources on immigrants when they could rebuild poor black communities," she says, pointing out that her own neighborhood, Kingsway East, once attracted African-American doctors, lawyers, and teachers.

National Journal

Only six percent of the city's Asian and Hispanic residents live in the black part of town north of Delmar Boulevard, census data shows. Ten times as many have settled south of it.

St. Louis Mayor Francis Slay says immigrants benefit the entire city, regardless of where they settle. Every business they open and every home they buy brings in more tax revenue, he told National Journal in a recent interview. But he acknowledges that the recent upheaval in Ferguson is a sign that government leaders need to work harder to address racial inequality.

"We need to do more," Slay says. "We have major challenges in this region."

There was a time when African-Americans prospered in St. Louis. The Ville, just north of the downtown, was the cultural heart of black St. Louis a century ago. African-Americans opened schools, hospitals, and businesses that boosted the local economy. Music legends like Tina Turner and Chuck Berry grew up here. So did Roscoe Robinson Jr., the first black four-star general in the U.S. Army.

Many of these black families arrived in the city during the Great Migration, when thousands of African-Americans left the hostile South to find factory work in the Rust Belt. St. Louis factories produced everything from cars and subway trains to kitchen stoves and shoes. By 1950, St. Louis was the eighth largest city in the country, with a population nearing 900,000.