Measles in America, 1928–2026
We beat measles once, but will it come back?
Project Tycho and CDC surveillance data · cases reported through the week ending October 3, 2026
This chart shows both a dramatic case for vaccination and, on closer inspection, a tenous moment for public health. The US eliminated measles in 2000. In 2026, the CDC has confirmed 4,080 cases as of October 8, the most since 1991. Kindergarten vaccination now sits below the herd-immunity threshold (95%) in most of the country.
Fetching this year’s counts from the CDC…
Data visualization
A chart that speaks without saying a word
Tynan DeBold and Dov Friedman of the Wall Street Journal published (2015) a grid of cases by state and year for seven diseases, with the year each vaccine arrived marked in a vertical line. It instantly went viral. It's perfect data stroytelling: The color is there, and then it isn’t. Mike Bostock later rebuilt it in Observable Plot with a purple-red ramp and a square-root scale, which this I borrowed.
Both versions stop in the early 2000s, where Project Tycho’s digitized weekly reports end. The grid above runs to the current week. The pre-vaccine era pattern shows elevated epidemics every two or three years as each new group of children reached school age. The CDC estimates three to four million Americans caught measles each year in that era, though only about half a million cases were ever actually reported.
After the vaccine was licensed in 1963, the color fades in less than a decade. A second dose was recommended in 1989 after outbreaks among vaccinated schoolchildren. By 2000, continuous transmission had ended everywhere in the country, which is the technical meaning of “eliminated.” At this scale, the most recent years look nearly white. But that might be misleading.
Don't call it a comeback
Looking closer at the last two years
As you can see, even with herd-immunity, a virus like measles can continue to circulate. Today's case rate wouldn't have registered as unusual in 1940s. So, our old color scale doesn't highlight the problem. This chart is calibrated on a more sensitive scale – each step in color is ten times the rate below it. Gray means no cases were reported that year. States are sorted by their rate since January 2025, and counts are printed where at least 25 cases were reported.
The CDC counted 2,289 confirmed cases in 2025 and three deaths. The first American measles deaths in a decade. The year began with an outbreak in Gaines County, Texas. In 2026, the count had passed 4,000 by early October. The largest totals this year are in Pennsylvania, South Carolina, and Utah, where one outbreak has now continued for more than a year. A regional commission of the Pan American Health Organization is expected to rule in November on whether the United States has lost its elimination status. Canada lost its in November 2025.
Ya herd?
Most states are below the immunity line
Measles is among the most contagious diseases we know. One case in a fully susceptible population generates 12 to 18 new ones. To stop it from spreading, roughly 95 percent of a community needs to carry two doses of MMR vaccine. That's a rule of thumb rather than a physical constraint. But, it is the target every public health system uses, and it is what the gray means on this map.
Each year the CDC collects kindergarten coverage figures from state immunization programs. In the 2019–20 school year the national rate stood at 95.2 percent. Since then it has eroded to 92.4 percent in 2025–26, while exemptions reached a record high. Drag the slider to watch states fall under the line, one school year at a time.
Number of states below 95 percent, by school year
A state average is a blunt instrument. The Economist’s county-level map from Johns Hopkins data shows exactly how much it conceals: coverage in a single county or school can be 20 points below the state figure. Outbreaks take hold in those pockets. The next chart is not as orderly as the map suggests it ought to be.
Coverage and cases
Lower coverage = more measles... mostly
Let's plot each state’s kindergarten coverage against its case count since January 2025. Generally, states below 95% immunization have about twice the median case rate of states above it. It's a noisy picture. Utah sits at 87 percent coverage but leads the country in case rate. New Mexico clears the threshold and still posts a higher rate than most states that don’t, because the West Texas outbreak crossed the border. Several states with low coverage have reported almost no cases, so far.
More experiments
About this page
1928–2001. Counts are from Project Tycho version 2.0, the University of Pittsburgh’s digitization of the weekly notifiable-disease tables the CDC and its predecessors published. For each state and year the page uses whichever figure is larger: the sum of the weekly reports, or the largest year-to-date total the state published that the following week’s report confirms. That rule eliminates a handful of mis-dated rows and single-week transcription spikes in the source. Each week is assigned to the MMWR year containing its Thursday. Tycho records only the weeks a state actually filed, so some state-years are incomplete: national totals typically run 5 to 25 percent below the CDC’s annual summaries, and 1992–93 run somewhat high. The shape of the history is solid; individual cells are approximate. New York is absent from Tycho between 1964 and 2001; those years, and a few other gaps, are filled from the state series published by Our World in Data. A hatched cell means no source has a figure.
2002–2022. State rates come from Our World in Data, which compiles the CDC’s annual Summary of Notifiable Diseases and NNDSS annual tables. Converted back to counts using Census population figures, they reconcile with the CDC’s published national total in every year – 44 cases in 2002, 1,274 in 2019.
2023 to now. Counts are the year-to-date totals in the NNDSS weekly tables, indigenous and imported cases combined, with New York City folded into New York. The current year and the year before are fetched live from data.cdc.gov when the page loads; if that fails, the page falls back to a copy saved on October 12, 2026 and says so under the headline. Weekly tables are provisional and lag the CDC’s own count: they sum to 2,026 cases for 2025 against the CDC’s final 2,289. State figures are the best available, but run low.
Rates are cases per 100,000 residents, using Census Bureau annual estimates via FRED; the most recent year’s population stands in for the current year. The District of Columbia is excluded from the grids because no state-level series covers it for 2002–2022. The color scale in Fig. 1 is a square root and tops out at 1,500 per 100,000; a few epidemic years in small states ran higher. Fig. 2 tops out at 10 per 100,000.
Coverage is the CDC’s SchoolVaxView estimate of two-dose MMR coverage among kindergartners, collected by states using methods that range from a census of every school to a sample survey – which means small differences between states fall within the noise. Montana has not reported since 2020–21 and Kansas did not report for 2025–26. Kindergarten coverage is a leading indicator; it is not a direct measure of immunity in the population at large.
Sources: Van Panhuis, W., Cross, A., Burke, D., Counts of Measles reported in the United States of America: 1888–2002, Project Tycho v2.0 (CC BY 4.0). CDC National Notifiable Diseases Surveillance System weekly tables. CDC Measles cases and outbreaks, October 8, 2026. CDC SchoolVaxView. Our World in Data, Reported measles case rate by state. U.S. Census Bureau resident population via FRED. CDC, History of measles. STAT, on the PAHO elimination review, August 6, 2026. Johns Hopkins, county MMR coverage study, 2025.
After Tynan DeBold and Dov Friedman, Battling Infectious Diseases in the 20th Century, Wall Street Journal, 2015, and Mike Bostock’s Plot recreation. Charts are drawn with Observable Plot and D3; state shapes are from us-atlas. The data is built by assets/measles/build-data.py in this site’s repository, and the CDC’s weekly and national counts are saved here every morning, so the page keeps working when the CDC can’t be reached.