In 2023, the US reported chlamydia at about 492.2 cases per 100,000 people, gonorrhea at 179.5, and primary and secondary syphilis at 15.8 CDC AtlasPlus, 2023. Washington, DC, and several Southern states sit far above these national baselines, while Idaho, Maine, and Connecticut consistently rank lowest. Rates reflect both real infection burden and how aggressively a state tests.
| Item | Value |
|---|---|
| DC | 1,228 |
| Louisiana | 792 |
| Alaska | 698 |
| Alabama | 651 |
| Georgia | 646 |
| US average | 492 |
| Iowa | 427 |
| Maine | 217 |
How to read STD rates by state
Rates are expressed as cases per 100,000 population, which lets you compare a small state against a large one fairly — a raw case count in California will dwarf Alaska's no matter what, but the per-100k rate puts them on equal footing. Every figure here is a reported rate, meaning it counts only infections that were diagnosed, confirmed, and submitted to public health surveillance.
That distinction matters more than people expect. Most chlamydia infections cause no symptoms at all, so a person never seeks care, never gets tested, and never enters the count. The CDC estimates the surveillance system catches only about 1 in 4 chlamydia infections CDC, 2023. The true burden is several times higher than any state number you'll see — these rankings measure detected disease, not all disease.
So a low state rate can mean two opposite things: genuinely less transmission, or simply less testing. Keep that in mind as you read — a high number often signals a place that's looking hard, not just a place that's sick. For the full national picture, see our US STD statistics overview.
Chlamydia rates by state: highest and lowest
Chlamydia is the most commonly reported bacterial STI in the country, and its state-level spread is wide. Washington, DC, leads by a large margin at 1,228 per 100k — more than double the national rate. Louisiana (792.4), Alaska (697.7), Alabama (651.1), and Georgia (646.4) round out the top five. Arkansas, Illinois, Delaware, Arizona, and Florida also rank among the highest.
At the other end, Maine reports the lowest rate at 217.4 per 100k, followed by Idaho (294.9), Connecticut (364.8), Kentucky (381.9), and Iowa (426.8). Because chlamydia is largely silent, these low numbers are partly a function of who's getting screened — a younger, more frequently tested population pushes a state's count up even when behavior is similar.
Gonorrhea rates by state: highest and lowest
Gonorrhea follows a similar geographic pattern but at lower overall numbers. DC again tops the list at 853.3 per 100k, with Alaska (310.9), Louisiana (288.4), Georgia (274.8), and Alabama (226.9) close behind. Florida, Illinois, Arkansas, Arizona, and California complete the highest-burden states.
Idaho reports the lowest gonorrhea rate at 39.6 per 100k — a striking gap from DC. Connecticut (113.3), Iowa (116.8), Hawaii (126.7), and Colorado (128.7) also fall well below the national figure. Gonorrhea more often produces noticeable symptoms than chlamydia, especially in men, so its reported rates may track real transmission a bit more closely than chlamydia's do.
Syphilis (P&S) rates by state: highest and lowest
Primary and secondary (P&S) syphilis are the early, most infectious stages — the chancre sore and the body-wide rash phase — and they're the stages public health watches most closely because that's when transmission and intervention both peak. DC leads at 39.9 per 100k, with Arkansas (29.2), Alabama (28.6), Louisiana (26.1), and Arizona (24.1) following. Alaska, Georgia, Florida, Delaware, and Colorado are also high.
Idaho records the lowest P&S rate at 3.8 per 100k, ahead of Maine (5.3), Connecticut (7.3), Michigan (8.4), and Iowa (10.3). Rising syphilis among people who can become pregnant has driven a parallel surge in congenital cases — 3,882 nationally in 2023, up from 2,163 in 2020, a 79% rise in three years. The geography of adult P&S syphilis closely mirrors the congenital syphilis crisis now unfolding in those same high-rate states.
How the three infections compare nationally
| Infection (2023) | US rate per 100k | Highest state | Lowest state |
|---|---|---|---|
| Chlamydia | 492.2 | DC (1,228) | Maine (217.4) |
| Gonorrhea | 179.5 | DC (853.3) | Idaho (39.6) |
| P&S syphilis | 15.8 | DC (39.9) | Idaho (3.8) |
Why STD rates vary so much between states
No single factor explains the spread. The biggest drivers cluster together in the same places, which is why the same handful of states keeps appearing at the top across all three infections:
- Surveillance and testing intensity — urban areas and well-funded health departments test more people, which detects more infections and pushes the reported rate up. A state isn't necessarily sicker; it may simply be looking harder.
- Poverty and healthcare access — higher poverty correlates with less insurance coverage and fewer primary care visits, which delays diagnosis and treatment and lets infections circulate longer in a community.
- Age structure — the peak STI age group is 15 to 24, so states and cities with more young adults carry a structurally higher rate.
- Population density — dense urban populations both transmit more readily and get tested more, a double effect that makes cities like DC stand out.
DC is the clearest example of why you can't read a number in isolation. Its rates are extreme outliers partly because a dense urban population with high testing uptake is being captured thoroughly — the figures reflect both genuine burden and excellent detection. The mirror image of that is a low-rate rural state where infections may be circulating undetected because few people are screened.
These same disparities show up in HIV. New HIV diagnoses ran highest in Georgia (25.5 per 100k), Florida (22.7), and Louisiana (22.5) in 2023, against a US rate of 13.7 AIDSVu, 2023 — the South again. You can explore the related picture of treatment access in our breakdown of HIV viral suppression by state.
What high state rates mean for your testing decisions
State rankings aren't trivia — they change the math on your own risk. If you live somewhere with high community prevalence, more of the partners in your local dating pool are infected, so the statistical risk of any single encounter is higher. That makes the case for routine screening stronger, not weaker.
If you're sexually active in DC, Louisiana, Alaska, or Alabama, the USPSTF-recommended annual screening isn't a box-ticking formality — it's statistically warranted by where you live. And because chlamydia in particular is usually silent, you can't rely on symptoms to tell you when to test. The practical move is simple: pick a cadence and stick to it. You can get tested at a clinic, through your primary care provider, or with an at-home kit, regardless of which state's number you fall under.