To determine the counties with the smallest income gaps in the nation, 24/7 Wall St. reviewed five-year estimates of the Gini Index of income inequality from the U.S. Census Bureau’s 2019 American Community Survey.
The Gini Index of income inequality summarizes income dispersion in an area on a scale from 0 to 1. A value of 0 indicates perfect equality — everyone in the area receives an equal share. A value of 1 indicates perfect inequality — only one recipient receives all the income.
Of the 3,220 counties or county equivalents, 3,142 had boundaries that fell within one of the 50 states or the District of Columbia.
Counties were excluded if the Gini Index was not available in the 2019 ACS, if there were fewer than 1,000 housing units, or if the sampling error associated with a county’s data was deemed too high.
The sampling error was defined as too high if the coefficient of variation — a statistical assessment of how reliable an estimate is — for a county’s Gini Index was above 15% and greater than two standard deviations above the mean CV for all counties’ Gini Indices. We similarly excluded counties that had a sampling error too high for their population, using the same definition.
The remaining 3,009 places were ranked based on their Gini Index. To break ties, we used the share of aggregate household income earned by the top 20% of households.
Additional information on average household income by quintile, share of aggregate household income by quintile, and median household income are also five-year estimates from the 2019 ACS.
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