The 2025 Annual Data Release used data from 2020-2022 for this measure.

Data Source

"National Center for Health Statistics - Mortality Files: Data on deaths and births were provided by NCHS and drawn from the National Vital Statistics System (NVSS). These data are submitted to the NVSS by the vital registration systems operated in the jurisdictions legally responsible for registering vital events (i.e., births, deaths, marriages, divorces, and fetal deaths). In prior years of the Rankings, Premature Death was calculated by the National Center for Health Statistics, but the Mortality-All County (micro-data) file was requested this year. This allowed County Health Rankings to calculate Premature Death and Life Expectancy themselves. While most calculations of mortality rates can be downloaded from CDC WONDER, the calculation of Years of Potential Life Lost and Life Expectancy requires raw data files." 

Measure Methods

• "Life Expectancy is an average: Life Expectancy measures the average number of years from birth a person can expect to live, according to the population's current mortality experience (age-specific death rates). Life Expectancy calculations are based on the number of deaths in a given time period and the average number of people at risk of dying during that period, allowing us to compare data across counties with different population sizes."

• "Life Expectancy is age-adjusted: Age is a non-modifiable risk factor, and poor health outcomes are more likely as age increases. Life Expectancy is age-adjusted to compare counties with differing age structures fairly."

• "What deaths count toward Life Expectancy?​​​​​: Deaths are counted in the county where the individual lived, regardless of where the death occurred."

• "Some data are suppressed: A missing value is reported for counties with fewer than 5,000 population-years-at-risk in the time frame."

• "Measure limitations: Life Expectancy includes mortality of all age groups in a population instead of focusing just on premature deaths and thus can be dominated by deaths of the elderly. This could draw attention to areas with higher mortality rates among the oldest segment of the population, where there may be little that can be done to change chronic health problems that have developed over many years. However, this captures the burden of chronic disease in a population better than premature death measures. Furthermore, the Life Expectancy calculation is complex and difficult to communicate. Methodologically, it can produce misleading results caused by hidden differences in age structure, is sensitive to infant and child mortality, and tends to be overestimated in small populations."

• "Can This Measure Be Used to Track Progress?: This measure can be used to track progress with some caveats. Life expectancy is a very long-term health outcome, the effects of which might not be seen for years or even decades. Life Expectancy as a measure also changes much more minutely than other mortality measures due to its calculation. Coupling these matters with the 3-year average provided in the County Health Rankings means that small changes may be difficult to detect, especially in small communities."

Source: Life Expectancy* | County Health Rankings & Roadmaps

References

• Centers for Disease Control and Prevention. Premature mortality in the United States: Public health issues in the use of years of potential life lost. Morbidity and Mortality Weekly Reports. 1986;35(suppl 2):1S-11S.

• Dranger E, Remington P. YPLL: A Summary Measure of Premature Mortality Used in Measuring the Health of Communities. Madison, WI: University of Wisconsin Population Health Institute. 2004: 5(7).

• Silcocks PB, Jenner DA, Reza R. Life expectancy as a summary of mortality in a population: statistical considerations and suitability for use by health authorities. Journal of Epidemiology & Community Health. 2001 Jan 1;55(1):38-43.

• Eayres D, Williams ES. Evaluation of methodologies for small area life expectancy estimation. Journal Epidemiology and Community Health. 2004; 58(3):243–9.