Jan. 28: Income equality is expected to be a major theme of President Obama's State of the Union address tonight. Explore the income equality of your county, based on data from the 2010 American Community Survey.

This was originally published on Nov. 4, 2011.

The chart below shows income inequality in the 818 largest counties in the U.S. Use the search box to find your county by address or ZIP code.

It uses what is known as the Gini index, a statistical measure that ranges from zero, which would describe a community in which every citizen has precisely the same income, to one, which would describe the opposite extreme, in which one person receives literally all of the income.