What It Measures

The JHU Measles Tracking project compiles measles case data from state and local health departments across the United States. Its county rows provide granular case-report context, but they do not independently establish formal outbreak status or a clean calendar-year state total.

How It Works

The tracking team aggregates publicly reported measles case data from state health department websites, press releases, and surveillance reports. Local Health Signal uses the cumulative county rows and their latest report dates for state detail, while CDC supplies the national total and formal national outbreak count.

What It Tells You

This data provides a detailed view of where measles case reports have appeared at the county level. It complements CDC national totals with geographic context and links readers toward state and local sources.

Limitations

Case counts may lag behind real-time reporting by health departments.
County rows are cumulative. A recent row date does not mean every case in that row occurred in 2026.
Recent report dates are not formal outbreak declarations, and Local Health Signal does not infer formal state outbreak status from them.
Not all states provide county-level data, so some cases may be reported only at the state level.
Case definitions and reporting practices vary between states.
This is a compiled dataset; the primary data comes from individual state and local health departments.