Methodology

Data Sources

HealthByCounty draws its data primarily from the CDC County Health Rankings & Roadmaps program, a collaboration between the Robert Wood Johnson Foundation and the University of Wisconsin Population Health Institute. This program compiles health data from multiple federal agencies and produces annual county-level health rankings for nearly every county in the United States.

Additional demographic and socioeconomic context comes from the U.S. Census Bureau American Community Survey (ACS) 5-Year Estimates (2019-2023), which provides population, income, and insurance coverage data at the county level.

All data is sourced from publicly available U.S. government datasets. We do not conduct original surveys or collect health data directly from individuals.

Health Metrics

We track the following county-level health metrics:

How Health Scores Are Calculated

Each county receives a health score from 0 to 100 using percentile-rank methodology. Here is how the process works:

1. Data collection: We pull the latest available health metrics from CDC County Health Rankings for all 3,143 US counties.
2. Normalization: Each metric is converted to a percentile rank across all counties. For metrics where lower is better (e.g., uninsured rate, premature death rate), the ranking is inverted so that a higher percentile always indicates a healthier county.
3. Composite scoring: The individual metric percentiles are combined into a single composite health score. Life expectancy, uninsured rate, and primary care access carry the most weight, as these are the strongest predictors of overall county health outcomes.
4. Score assignment: The final composite is scaled to a 0-100 range where 100 represents the healthiest county and 0 the least healthy. A score of 75 means the county is healthier than 75% of all US counties.

Geographic Coverage

HealthByCounty covers all 3,143 counties and county-equivalents in the United States, including parishes (Louisiana), boroughs (Alaska), and independent cities (Virginia). Coverage spans all 50 states and the District of Columbia.

Some counties may have incomplete data for certain metrics. When a metric is unavailable for a county, it is marked as "N/A" and excluded from the composite score calculation for that county. Counties with insufficient data across multiple metrics may not receive a health score.

Data Freshness

The CDC County Health Rankings are released annually, typically in the spring. Our data reflects the most recently published rankings (2024 release). We update our dataset within 30 days of each new CDC release.

Census ACS data used for supplemental metrics (insurance coverage, demographic context) comes from the 2019-2023 5-Year Estimates, the most recent available at the time of publication. Five-year estimates provide greater statistical reliability for small counties compared to single-year estimates.

AI-Generated Content Disclosure

HealthByCounty uses AI (Claude by Anthropic) to generate descriptive narratives for state and county pages. These narratives summarize and contextualize the underlying government data — they do not introduce new data points or medical claims.

All AI-generated content is:

• Based exclusively on verified government data (CDC, Census Bureau)
• Reviewed for accuracy against the source data
• Clearly informational — not medical advice
• Regenerated when underlying data is updated

All statistics, scores, tables, and rankings on this site are computed directly from government source data. AI is used only for prose narratives, not for data calculations or score generation.

Limitations

• Health scores are composite estimates and should not be used as a substitute for professional medical or public health guidance.
• County-level data may not reflect conditions in specific neighborhoods or communities within a county.
• Data availability varies by county size. Smaller counties may have less reliable estimates due to sampling margins in survey-based data.
• Health outcomes are influenced by many factors not captured in this dataset, including environmental conditions, access to specialty care, and social determinants of health.