Blacklegged ticks are widely distributed across the eastern United States and along the Pacific coast. The eastern blacklegged tick (Ixodes scapularis) spans from the Northeast down through the Mid-Atlantic, Southeast, and into the upper Midwest, while its close relative, the western blacklegged tick (Ixodes pacificus), lives along the Pacific coast, particularly in northern California. Knowing where these ticks live, both geographically and at ground level, is the key to avoiding them.
Geographic Range Across the US
The eastern blacklegged tick is the more widespread of the two species. It has been documented in counties across the entire eastern half of the country, from Maine to Florida and west through Minnesota, Iowa, and Texas. Its range has expanded significantly over the past two decades. In Virginia, for example, the tick was once considered established mainly in eastern coastal counties but is now found throughout most of the state, with some of the highest densities appearing at higher elevation sites rather than just the coast.
The western blacklegged tick occupies a narrower band along the Pacific coast. Northern California is its stronghold, though it also occurs in Oregon and Washington. Both species transmit Lyme disease, but the eastern blacklegged tick is responsible for the vast majority of cases in the US. Lyme disease incidence varies dramatically even within a single state, with localized hotspots appearing in otherwise low-risk areas. These ticks are also found across temperate regions of southern Canada, Europe, and Asia, where related Ixodes species carry the same pathogens.
Habitats That Support Tick Populations
Blacklegged ticks live in forested and wooded areas where they can find both hosts and the moisture they need to survive. Deciduous and mixed forests with a thick layer of leaf litter on the ground are ideal. The leaf litter acts as a humidity buffer: relative humidity at ground level in these environments frequently reaches 100%, which is critical for tick survival. Nymphal ticks, the life stage most likely to transmit Lyme disease, can dry out and die within 48 hours if deprived of moisture. Extended exposure to humidity below about 82% for more than eight hours can be lethal, even if conditions improve afterward.
This moisture dependence explains why you won’t typically find blacklegged ticks in open, sunny, dry areas like mowed lawns or paved trails. They concentrate where the canopy holds in humidity and the ground stays damp under decomposing leaves. Forest edges, brushy undergrowth, and areas with dense ground-level vegetation all provide the conditions ticks need.
Where Ticks Concentrate in Your Yard
If you live near woods, the highest-risk zone in your yard is the border where lawn meets forest. A Connecticut study published in Environmental Entomology found that nymphal blacklegged tick densities were greatest in forested areas closest to lawn edges where leaf litter or understory vegetation was present, as well as on short lawns directly adjacent to woodland edges. The wooded side of that boundary, where tree cover creates shade and the ground is blanketed in leaves with scattered undergrowth, had the most ticks.
Stone walls were another hotspot. Rodents, which are key hosts for immature ticks, nest inside the crevices of stone walls, creating a reliable supply of blood meals. Woodpiles, surprisingly, did not attract many ticks. Researchers suspect this is because woodpiles lack the permanence that makes stone walls appealing rodent habitat. Areas near bird feeders were also low in tick density.
The practical takeaway: if you’re doing yard work, gardening near a forest edge, or letting kids play close to a tree line, that’s where tick checks matter most. The middle of a well-maintained lawn is relatively low risk.
Animal Hosts That Carry Ticks
Blacklegged ticks feed on different animals at each life stage, and these hosts determine where ticks show up. Adult ticks feed primarily on white-tailed deer and coyotes. Deer don’t transmit Lyme disease themselves, but they’re the main reproductive hosts for adult ticks, so areas with large deer populations tend to have more ticks. Neighborhoods where deer browse through yards regularly face higher exposure.
Nymphal and larval ticks feed on smaller animals. In the Southeast, lizards like the broad-headed skink and eastern fence lizard are primary hosts for nymphs. Larvae feed on skinks, smaller lizards, and songbirds like the Carolina wren. In the Northeast and Midwest, the white-footed mouse is the most important host for immature ticks and also the primary reservoir for the Lyme disease bacterium. Cottontail rabbits may also play a significant role in Lyme transmission in some regions. Essentially, anywhere you find small mammals, ground-dwelling birds, and deer sharing wooded habitat, you’ll find blacklegged ticks.
When Ticks Are Actively Seeking Hosts
Blacklegged ticks don’t disappear in cooler weather the way many people assume. They are active roughly between 0°C (32°F) and 30°C (86°F), though their host-seeking behavior increases as temperatures rise within that range. Adults have been collected even on days when the average air temperature dropped to about −1°C (30°F), although in much lower numbers than on warmer days. A practical threshold for noticeable questing activity is around 4°C (39°F).
Humidity matters just as much as temperature. When relative humidity rises above about 40%, the number of actively questing ticks increases. Below that level, ticks retreat deeper into the leaf litter to rehydrate. This means warm, humid days after rain are peak conditions for encountering ticks, while hot, dry, windy days suppress their activity. In much of the eastern US, nymphs are most active from late spring through midsummer, while adults quest in fall and again in early spring whenever temperatures allow.
Lyme Disease Risk Varies by Location
Not every blacklegged tick carries Lyme disease, and infection rates vary enormously by region. The Northeast and upper Midwest have the highest rates of infected ticks, with states like Connecticut, Massachusetts, New York, Wisconsin, and Minnesota reporting the most cases year after year. In the Southeast, blacklegged ticks are present but feed more often on lizards, which don’t carry the Lyme bacterium, so infection rates in ticks tend to be lower.
Risk can also differ from one county to the next within the same state. Interactive maps from public health agencies show that localized hotspots exist in states that are otherwise considered low incidence. If you’re trying to assess your personal risk, county-level data is far more useful than state-level generalizations. The CDC maintains county-by-county maps showing where blacklegged ticks have been documented, which can help you understand the specific risk in your area.