To determine America’s least educated ZIP codes, 24/7 Wall St. reviewed five-year estimates of the percentage of adults 25 years and over with at least a bachelor’s degree from the U.S. Census Bureau’s 2019 American Community Survey.
We used ZIP Code Tabulation Areas — a Census geography type which defines areal representations of United States Postal Service ZIP codes (USPS ZIP codes do not define geographic boundaries but instead are a network of mail delivery routes in a service area). We refer to Census ZCTAs as ZIP codes.
Of the 33,120 ZIP codes the census publishes data for, 32,989 had boundaries that fell within one of the 50 states or the District of Columbia.
ZIP codes were excluded if bachelor’s degree or higher attainment rates were not available in the 2019 ACS, if the ZIP code’s 25 and older population was less than 1,000, or if the sampling error associated with a ZIP code’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 ZIP code’s bachelor’s degree or higher attainment rate was above 15% and greater than two standard deviations above the mean CV for all ZIP codes’ bachelor’s degree or higher attainment rate. We similarly excluded ZIP codes that had a sampling error too high for their 25 and over population estimates, using the same definition.
The remaining 20,112 ZIP codes were ranked based on the share of adults 25 years and over with at least a bachelor’s degree.
Additional information on the share of adults 25 years and over who have completed at least high school or its equivalent, median household income, unemployment rates for the 16 and older population in the civilian labor force, and population figures are also five-year estimates from the 2019 ACS.
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