Life expectancy in the United States has either fallen or remained flat over the last few years, according to the Centers for Disease Control and Prevention. The average life expectancy at birth is 78.6 years, down from 78.9 years in 2014. Life expectancy is one of the main measures of a population’s overall health, so the declines are concerning.

Still, life expectancy varies significantly across the United States. Different aspects, from socioeconomic factors to climate to culture and behaviors can affect life expectancy in an area. And there are some parts of the country where the average resident can expect to live several years longer than the average American.

To determine the counties where people live the longest, 24/7 Tempo reviewed 2014 county-level life expectancy at birth figures from the Institute for Health Metrics and Evaluation, a global research center affiliated with the University of Washington. Independent cities or census areas, which are treated as county equivalents by the U.S. Census Bureau, were not included in our analysis.

Residents of counties with longer life expectancy tend to exhibit the kind of healthy behaviors that can help lead to longer lives. Relatively fewer adults in these counties smoke or are obese, and more tend to be physically active. Not surprisingly, based on behavioral measures like these, many of these counties rank among the healthiest in the country. Here is the full list of the healthiest counties by state.

The association between wealth and longevity is not fully understood but well established. According to a 2016 study published in the Lancet, the richest 1% of Americans live on average nearly 15 years longer than the poorest 1%. In 44 of the 50 counties on this list, the poverty rate is lower than the national rate of 14.6%.

In fact, many of these counties are high-income areas — some even rank among the wealthiest counties in the country. Here is a full list of the richest counties by state.

Click here to see the counties where people live the longest
Click here to read our methodology