America spent an estimated $9,451 per person on healthcare in 2015, by far the most of any country. However, among wealthy, industrialized nations, the U.S. has the largest share of residents not getting the medical care they need due to financial costs. Among the 35 member nations of the Organization for Economic Co-operation and Development, America is the only country without universal health coverage. This inconsistent coverage and care can create large disparities in health outcomes between populations.

For the first time in decades, life expectancy in the United States fell in 2015. With a life expectancy at birth of 78.8 years, the U.S. ranks 28th among OECD countries. In addition, the U.S. is expected to fall even further behind other countries in the future. By 2030, life expectancy in the U.S. is expected to be on par with the Czech Republic for men and Croatia and Mexico for women.

Poor life expectancy in the U.S. is partially caused by differences in quality of and access to care, as well as a number of socioeconomic conditions that can affect health outcomes. As a result, longevity varies significantly from state to state. Hawaiians have the longest life expectancy, of 81.2 years. By contrast, the life expectancy in Mississippi is only 74.8 years, the shortest of any state. 24/7 Wall St. reviewed the average life expectancy at birth in each of the 50 states.

Click here to see the states with the longest and shortest life expectancy.

Longevity is a complex measure, and the discrepancy between states is due to many factors. Whether a state’s population tends to engage in healthy or unhealthy behaviors is one component.

High rates of smoking, for example, can reduce life expectancy statewide. Smoking is the leading cause of premature death in the U.S., with smokers dying 10 years earlier on average compared to nonsmokers. The 10 states with the shortest life expectancy all have smoking rates higher than the national average. Nine of the 10 states with the longest life expectancy have a lower smoking rate than the nation as a whole.

Following smoking, obesity is the leading cause of premature death. Obese individuals are more likely to have heart disease, stroke, type 2 diabetes, certain types of cancer, and other illnesses. In addition, those who are obese tend to exercise less, which can decrease longevity even further. Leading an active lifestyle has been shown to increase longevity, and states with a high share of sedentary individuals tend to have a lower life expectancy.

Many socioeconomic issues also play a role in a state population’s longevity, and income is one of the most important indicators. Between Mississippi and Hawaii — the states with the shortest and longest life expectancy, respectively — the gap between the typical household income is over $30,000. In addition, the 10 states with the greatest longevity all have household incomes over the national median, and the typical household earns less than the median in all of the 10 states with the shortest life expectancies.

While it has been a historical trend that wealthy individuals live longer than their poorer counterparts, this gap has widened in the past several decades. In 1970, a 50 year old woman in the bottom 10% of earners had a life expectancy of roughly 80.4 years. Women of the same age in the top 10% of earners had a life expectancy of 84.1 years.

In the following two decades, life expectancy for the top earners rose by 6.4 years. During the same period the life expectancy for women in the bottom income bracket didn’t increase at all. Health outcomes lagging behind in the poorest populations partially account for the low life expectancy in the U.S. compared to most other wealthy countries.

To determine the states with the longest and shortest life expectancies, 24/7 Wall St. reviewed 2013 life expectancy at birth figures provided by the Institute for Health Metrics and Evaluation, a global research center affiliated with the University of Washington. Obesity rates and smoking rates were obtained from County Health Rankings & Roadmaps program, a collaboration between the Robert Wood Johnson Foundation and the University of Wisconsin Population Health Institute and are for 2014. Median household income is from the U.S. Census Bureau’s 2015 American Community Survey.

These are the states with the longest and shortest life expectancies.