Welcome to the United States of Inequality.

The map below, based on data from the Census Bureau’s 2013 American Community Survey, shows the most unequal counties in America. In this case, inequality is derived using the Gini coefficient, which is a statistical measure of the gap between the rich and the poor. The index is based on a scale from 0 to 1, where 0 represents total equality and 1 represents total inequality.

Counties with high inequality are shaded in red. Counties with low inequality are shaded in yellow. Areas with no shading represent counties that have fewer than 65,000 people, as the Census does not collect annual inequality data for small counties.

As you can see, inequality tends to cluster around big cities. Metropolitan areas like Manhattan, San Francisco and Washington, D.C., are situated in some of the most unequal counties in the U.S.

Below is a list of 20 counties with the highest inequality, based on their corresponding Gini coefficients, according to the recent Census data. Though they're ranked here, it's important to note that the margins of error differ for these counties. Putnam County, Tennessee, has the highest Gini coefficient but also a very high margin of error. Your mileage may vary.

1. Putnam County, Tennessee 0.6286

2. New York County, New York 0.6012

3. Nacogdoches County, Texas 0.5634

4. Orleans Parish, Louisiana 0.5576

5. Fairfield County, Connecticut 0.5508

6. Fulton County, Georgia 0.5479

7. Monroe County, Florida 0.5477

8. Essex County, New Jersey 0.5409

9. Troup County, Georgia 0.5395

10. Bowie County, Texas 0.5366

11. Richmond city, Virginia 0.5352

12. District of Columbia, District of Columbia 0.532

13. Collier County, Florida 0.531

14. Westchester County, New York 0.5299

15. San Francisco County, California 0.5283

16. Christian County, Kentucky 0.5276

17. Baltimore city, Maryland 0.5269

18. Cabell County, West Virginia 0.5255

19. Potter County, Texas 0.5251

20. Marin County, California 0.5244

Map by Alissa Scheller. Data analysis by Ben Walsh.