CDC WONDER and FIPS Codes: Health Data by Geography
The CDC WONDER database is one of the most comprehensive sources of county-level health and mortality data. Here's how it uses FIPS codes.
The Centers for Disease Control and Prevention (CDC) WONDER (Wide-ranging ONline Data for Epidemiologic Research) database provides public access to a wide range of public health datasets, most of which are available at the county level using FIPS codes. The most commonly used WONDER datasets are Underlying Cause of Death (going back to 1999), Multiple Cause of Death, Natality (births), and the Compressed Mortality File. For public health researchers, epidemiologists, and health policy analysts, WONDER is an indispensable resource.
WONDER uses county FIPS codes as the standard geographic identifier for county-level data. When downloading data via the WONDER interface, the results include a "County Code" column containing the 5-digit FIPS code, directly joinable to Census demographic data, BLS employment data, and other federal datasets. A common research design: join CDC mortality rates by county to Census poverty rates and educational attainment to analyze socioeconomic determinants of health outcomes. The join key is the county FIPS code.
One important limitation of WONDER is that death records for counties with very small counts are suppressed to protect privacy — counties with fewer than 10 deaths in a category show suppressed values. This affects research on rare causes of death in rural counties. For King County, WA (population ~2.3M), suppression is rarely an issue, but for many rural counties it requires aggregation to multi-year windows or broader geographic levels.
The CDC also publishes the Behavioral Risk Factor Surveillance System (BRFSS), the National Health Interview Survey (NHIS), and the Social Vulnerability Index (SVI) — all using county FIPS codes. The SVI assigns a composite vulnerability score to each county based on Census data and is widely used in emergency preparedness and public health planning. Browse county profiles like Harris County (48201) to see geography context for these datasets, or use the federal data guide for a broader overview.
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