Ticks live in every part of the contiguous United States, and at least one medically important species is established in all 48 lower states. Alaska has no naturally occurring tick populations, and Hawaii hosts only the brown dog tick. Where you live determines which species you’re most likely to encounter, what diseases they carry, and when during the year they’re most active.
The Eastern US Has the Highest Tick Diversity
The eastern half of the country is home to the greatest variety and density of tick species. The blacklegged tick (often called the deer tick) is widely distributed across the entire eastern US and is the primary carrier of Lyme disease, anaplasmosis, and babesiosis. The lone star tick covers a similarly broad range across the Northeast, South, and Midwest, and is linked to a red meat allergy called alpha-gal syndrome. The American dog tick is found throughout the region east of the Rocky Mountains and can transmit Rocky Mountain spotted fever and tularemia.
The Gulf Coast tick is concentrated in the Southeast but has established smaller populations in parts of the Northeast, Midwest, and Southwest. If you live anywhere from New Jersey to Texas and spend time outdoors, you’re in range of at least three or four tick species simultaneously.
The West Coast and Mountain States
The Pacific coast has its own version of the deer tick: the western blacklegged tick. Its core range spans California, western Oregon, and western Washington, with isolated populations recorded in Utah and Arizona. This tick thrives in the cooler, wetter zones west of the Cascade and Sierra Nevada ranges but is largely absent from the dry eastern sides of Oregon and Washington and from southern California’s arid interior.
In the Rocky Mountain states, the Rocky Mountain wood tick lives at elevations between 4,000 and 10,500 feet. Despite its name lending the title to Rocky Mountain spotted fever, this species occupies a relatively narrow band of mountain habitat compared to the sprawling ranges of eastern ticks. A related species, recently described by scientists, fills a similar role west of the Rockies.
An Invasive Species Spreading Fast
The Asian longhorned tick was first detected outside a port inspection site in New Jersey in November 2017. As of early 2024, it has been confirmed in 20 states stretching from New England to the Deep South and as far west as Missouri and Arkansas. Confirmed states include Connecticut, Massachusetts, Rhode Island, New York, New Jersey, Delaware, Maryland, Pennsylvania, Virginia, West Virginia, North Carolina, South Carolina, Georgia, Kentucky, Tennessee, Ohio, Indiana, Illinois, Missouri, and Arkansas.
This tick is unusual because females can reproduce without mating, allowing a single tick to establish a new population. It feeds on livestock, wildlife, pets, and people. Researchers are still working out the full disease risk it poses in the US, but in its native range in East Asia it transmits a virus that causes severe fever with low platelet counts.
The One Tick That Lives Indoors
The brown dog tick is the only common US species that can complete its entire life cycle inside your home. It’s found worldwide and is the sole tick species established in Hawaii. Unlike other ticks that need forests or grasslands, this one thrives in kennels, houses, and anywhere dogs live. In the southwestern US and along the US-Mexico border, it transmits Rocky Mountain spotted fever, making it a particular concern in those regions.
When Ticks Are Most Active by Region
There is no single “tick season.” Activity depends on both species and geography, and some part of the country has active ticks in every month of the year.
Spring is when most people think of ticks, and for good reason. Adult American dog ticks and lone star ticks emerge in force starting in March, and May is consistently the most tick-heavy month nationwide. Summer stays just as busy, but the threat shifts: tiny nymph-stage blacklegged ticks are active from June through August. These are harder to spot (roughly the size of a poppy seed) and are responsible for most Lyme disease transmission.
Fall catches many people off guard. Adult blacklegged ticks surge in the Northeast from September through November, often appearing after the first frost when people assume the danger has passed. Winter brings quiet to most of the country, but tick activity continues in the Deep South and along the West Coast, where western blacklegged ticks remain active in California, Oregon, and Washington through December, January, and February.
Specific Habitats Where Ticks Concentrate
Ticks don’t roam open ground looking for hosts. They wait in very specific microhabitats where humidity keeps them alive and animal traffic brings hosts within reach. Understanding these spots matters whether you’re hiking a trail or walking across your backyard.
The highest-risk natural habitat is the ecotone: the transitional zone where forest meets open grass. Public parks, trail edges, and the brushy border between a mowed lawn and woodland are prime tick territory. Leaf litter on the forest floor is where nymph-stage ticks concentrate, sheltered under the canopy where moisture stays high. Adult American dog ticks are more drought-tolerant and will quest in open meadows, roadsides, and even beachgrass.
Your Yard
Research on residential properties in the New York City area found that specific yard features dramatically increase the odds of finding ticks. Log and brush piles were the strongest predictor, increasing the likelihood of finding the Asian longhorned tick by 3.6 times and the lone star tick by 4 times. Bird feeders also attract tick-carrying wildlife: about a third of yards with feeders had ticks present. Even the choice of ground cover matters. Woodchips and gravel along yard borders were associated with a 2.3-fold increase in lone star tick presence.
Other risk factors include proximity to woodland, lack of fencing (which allows deer access), and providing food or shelter for feral cats. More than half of yards that had food or shelter for feral cats also had ticks. If your property backs up to forest, keeping a clear buffer zone between the tree line and your living space is one of the most effective ways to reduce the number of ticks in your yard.
Tick Ranges Are Expanding
The geographic picture described above is not static. Tick-borne disease cases have increased in both number and geographic spread over recent decades, driven in part by expanding tick ranges. Changes in land use, the availability of animal hosts like deer and mice, and shifting climate patterns all contribute. The American dog tick alone has been recorded in 45 of the 48 contiguous states, though established populations at the county level are not well documented everywhere, suggesting the true range is likely broader than current maps show.
The blacklegged tick has pushed steadily north and west from its stronghold in the Northeast and upper Midwest. The lone star tick, once considered a southern species, is now well established in the Northeast. The Asian longhorned tick went from a single New Jersey county to 20 states in under seven years. If you live in an area where ticks weren’t a concern a decade ago, that may no longer be the case.