Inner urban areas are being repopulated and revived.

The long-standing urban-suburban divide in education, income, race and other characteristics is being turned on its head as college-educated Millennials crowd into U.S. cities, new research shows.

Putting urban neighborhoods under a microscope, a University of Virginia researcher has concluded that the traditional urban “donut” pattern — a ring of thriving suburbs surrounding a decaying city center — is being replaced by a new pattern: a thriving urban core surrounded by a ring of suburbs with older housing, older residents and more poverty.