Crain’s Chicago Business discusses the activity taking place in Chicago’s Loop and the surrounding area, an area it now calls the “mega-Loop”:

This is the new economic engine of the metropolitan area and, increasingly, the rest of Illinois. And it has reached a critical mass, data suggest, enabling its growth to be self-perpetuating, as more jobs downtown attract more residents to move nearby, which, in turn, becomes a magnet for more employers to join the inward migration.

The Chicago Loop long has been one of the world’s greatest job centers, of course. For much of its history, though, downtown emptied out after office hours. And as the city aged and its population declined, the suburbs rose to become the preferred home to generations of young families and the tollways became employment corridors of their own.

In recent years, those trends have reversed. After decades of watching the suburbs boom (often at the city’s expense), Chicago now is outperforming the surrounding area by almost any measure—jobs, income, retail sales and residential property values, to name a few—despite the loss of 200,000 people in the 2010 census.

The city is so hot that this expanded downtown is adding residents faster than any other urban core in America, according to U.S. Census Bureau data.

“In the year 2020, no matter how many condos are built or sold, Chicago is likely to be a nest of center-city affluence unequaled in size—or even approached—by anyplace in America,” journalist Alan Ehrenhalt writes in “The Great Inversion and the Future of the American City.”…

There’s no question, however, that the mega-Loop is benefiting from a back-to-the-city movement that is reviving urban centers elsewhere in the U.S. In Chicago, the trend appears to be sustainable. “This is a pattern that has developed for the last 30 years, and it has only strengthened,” says Columbia University sociologist Saskia Sassen, author of “The Global City.”

These are some big claims and it will take some years to see how the longer trend plays out. As the article notes, there are a lot of factors at work including a global economy, a variety of serious social issues in Chicago, and growth patterns in the Chicago region where the outer collar counties are gaining population.

If the glitzy downtowns continue to grow as do the more exurban areas, perhaps it is the closer suburbs that are left out. These suburbs were likely founded between the mid 1850s and 1960s and are long past the era of rapid suburban growth. While researchers have noted troubling trends among inner-ring suburbs, communities adjacent to big cities, this might extend further out as growth is centered on the downtown and at the fringes.