The gap between the wealthy and the poor is most extreme in several of the United States’ most prosperous and largest cities.

The economic divides in Atlanta, San Francisco, Washington, New York, Chicago and Los Angeles are significantly greater than the national average, according to a study released last week by the Brookings Institution, the Washington-based think tank. It suggests that many sources of both economic growth and income inequality have co-existed near each other for the past 35 years.