The Elder Economic Security Standard Index (Index) offers a cost of living standard for independent, community-dwelling singles and couples aged 65 and older, calculated for every county in the United States. The Index includes local cost of housing, food, transportation, healthcare, and other expenses. Annual costs of living are calculated under three housing scenarios: homeowners with a mortgage, homeowners without a mortgage, and renters. Across these scenarios, the Index shows that cost of living increased 1% - 7% for seniors from 2011 to 2015. National summaries indicate that for singles in good health, annual Index values range from $19,872 to $30,516; for couples, they range from $30,288 to $40,932. Single homeowners in good health and without a mortgage have the lowest cost, whereas couple homeowners in poor health and with a mortgage have the highest cost of living. We illustrate spatial variation in cost of living for older adults using maps and spatial analysis techniques. Further analysis highlights gaps between cost of living and the typical Social Security benefit; these gaps also differ substantially across geographic areas. Locations in which the cost of living for seniors has increased most markedly between 2011 and 2015 are identified. We also identify gender, race, and age segments within the older population that are most substantially impacted by spatial inequality in cost of living for older adults. Resources for adults who are older, female, or of a racial or ethnic minority group are more likely to fall below the Index value.