Education · Surveillance data
Lyme, mapped
Where reported Lyme disease actually lands, state by state, from CDC's own surveillance data — with the counting rules drawn on the map, because a map without them is a rumor with a legend.
What this map shows
Each state is coloured by how many Lyme disease cases were reported to CDC for the year you choose — any year from 1992 to 2023. The bins are powers of ten, because in a single year one state can report tens of thousands of cases while another reports a handful, and any narrower scale would put almost every state in one bucket. The exact count for every jurisdiction is in the table under the map, and looking a state up draws its whole 1992–2023 series — the colours orient, the numbers answer.
Nothing here reads from any LymeHQ record. This map is built from public, external sources only, and every layer on it names its source, its date, and what it cannot say — on the map itself, where a screenshot keeps them.
Reported Lyme disease cases by state, 2023
2023 · CDC Lyme disease surveillance
89,469 cases reported nationally for 2023
Counting rules changed in 2008 and 2022 — a jump across those years is partly surveillance artifact, not epidemiology.
- 1–9
- 10–99
- 100–999
- 1,000–9,999
- 10,000+
- No count published — not zero risk
Not on the map: 54 withheld below state level by CDC (too few to show). Real cases, no state to draw them in.
Every jurisdiction with a published count for 2023 (44), as a list
| Jurisdiction | reported cases |
|---|---|
| New York | 22,173 |
| Pennsylvania | 16,671 |
| Massachusetts | 9,715 |
| New Jersey | 7,224 |
| Wisconsin | 6,283 |
| West Virginia | 3,242 |
| Connecticut | 3,239 |
| Maine | 2,942 |
| Minnesota | 2,938 |
| Rhode Island | 2,852 |
| Maryland | 2,470 |
| Virginia | 1,747 |
| New Hampshire | 1,573 |
| Vermont | 1,445 |
| Ohio | 1,307 |
| Michigan | 1,150 |
| Illinois | 372 |
| Delaware | 349 |
| Florida | 271 |
| Indiana | 257 |
| North Carolina | 228 |
| Iowa | 212 |
| Kentucky | 120 |
| California | 109 |
| District of Columbia | 108 |
| Oregon | 61 |
| South Carolina | 55 |
| Tennessee | 50 |
| Alabama | 34 |
| Colorado | 29 |
| Texas | 27 |
| Washington | 25 |
| Georgia | 17 |
| Utah | 16 |
| Missouri | 15 |
| Louisiana | 14 |
| Nevada | 14 |
| North Dakota | 12 |
| Arizona | 11 |
| Idaho | 11 |
| Kansas | 8 |
| New Mexico | 8 |
| Montana | 6 |
| South Dakota | 5 |
No published count for 2023 (not reported, or withheld below CDC’s display floor — not zero): Alaska, Arkansas, Hawaii, Mississippi, Nebraska, Oklahoma, Wyoming.
What this layer cannot say
- These are reported cases under the national surveillance definition, not infections — CDC-published claims analyses estimate roughly 476,000 people are diagnosed with and treated for Lyme disease each year in the United States (Kugeler et al., Emerging Infectious Diseases, 2021), several times these totals.
- 44 jurisdictions have a published count for 2023. A hatched state has no published state-level count — it did not report, or its count was below CDC's display floor and was withheld into the suppressed line. Either way, absence here is not evidence of absence there, and it is never zero risk.
- Counting rules in force: Case definition revised: high-incidence jurisdictions count laboratory evidence alone, and most cases are classified Probable. Jumps at this boundary are partly surveillance artifact, not epidemiology. Comparing years across a definition change compares the definitions too.
Reading the empty states
The hatched states are the most important thing on this map, and the easiest to misread. A hatched state has no published state-level count for that year — and that absence is ambiguous by design: the state may not have reported to CDC at all, or it may have reported a count small enough that CDC withheld it rather than point at individual people. What the hatching never means is zero. Blacklegged ticks do not respect surveillance boundaries, and a state that left the published record did not stop having Lyme. Reading absence as safety is the one mistake this map is built to refuse — which is why an empty state is hatched and labelled rather than painted the palest green.
Where the numbers come from
The map renders the same verified CDC snapshot as the case counts guide, pulled from data.cdc.gov and refused unless every year’s state figures reconcile exactly to the national total. A scheduled check re-derives sampled years and state-years from the live source and goes red if they no longer match this snapshot — a red means CDC revised the data, and the snapshot is re-pulled.
Data retrieved from data.cdc.gov on 2026-08-27
Related guides: Case counts & trends · Tick prevention · Education library