Lewis and Clark Caverns State Park

Lewis and Clark Caverns State Park, in the Jefferson River canyon between Whitehall and Three Forks in southwestern Montana, is Montana’s first and most celebrated state park — and the home of one of the finest limestone cavern systems in the Pacific Northwest, with large decorated chambers filled with stalactites, stalagmites, flowstone columns, cave coral and helictites formed over millions of years by water percolating through the Madison Limestone.

The caverns are named for Meriwether Lewis and William Clark, whose Corps of Discovery passed through the Jefferson River valley in 1805, though the caves were not actually visited by the expedition. The park encompasses 3,015 acres of spectacular Jefferson River canyon scenery — limestone cliffs, ponderosa pine and juniper slopes, and the broad river valley — offering hiking, camping and wildlife watching above ground and guided cave tours below. Lewis and Clark Caverns is a cherished geological icon of southwestern Montana.

May through September is the cave tour season — the guided tours operate daily during this period, with the most frequent departures in July and August. The cave interior is a constant 48°F year-round (bring a jacket); the cave experience is essentially identical in any season, but tours are only offered May-September. Summer (June through August) is the finest season for the surface hiking and camping as well — the Jefferson River canyon is green and the wildflowers on the limestone slopes are at their peak in June. May and September are excellent shoulder months with fewer visitors and cooler surface temperatures for hiking. The Jefferson River fishing is good from June through October. The cave is the year-round draw (but tour season is May-September); the canyon hiking and camping are finest in summer.

Lewis and Clark Caverns were first noted by non-Native Americans in the 1880s when a group of hunters discovered the cave entrance on the limestone cliffs above the Jefferson River. The caverns were promoted as a tourist destination in the late 19th century and were initially called Morrison Cave (for one of the early claimants); the name was changed to Lewis and Clark Caverns when they were established as Montana’s first state park in 1937, honoring the Corps of Discovery’s passage through the Jefferson River valley in 1805 (Lewis and Clark camped at the confluence of the Jefferson, Madison, and Gallatin rivers — the Three Forks area, just east of the park — in July 1805 and named the rivers for members of Jefferson’s cabinet). The cave system was known to the Shoshone and other Native American peoples long before European contact. The state park was developed with CCC labor in the late 1930s.

Lewis and Clark Caverns formed in the Madison Limestone — a Mississippian-age (approximately 340-360 million years old) marine limestone that underlies much of southwestern Montana and forms the cliff-face exposures above the Jefferson River. The cave system was dissolved from the Madison Limestone by slightly acidic groundwater (carbonic acid from rainwater and soil CO2) over millions of years, creating the cave passages and chambers. The cave’s speleothems (stalactites, stalagmites, flowstone, helictites and cave coral) formed as calcium carbonate-saturated water dripped and flowed into the cave, depositing calcite as it de-gassed CO2 — a process that continues today in the active, damp sections of the cave. The helictites (twisted, gravity-defying calcite formations) are among the finest in Montana. The Madison Limestone, the dissolution by acidic groundwater, and the calcite speleothem deposition created the Lewis and Clark Caverns.

Lewis and Clark Caverns State Park’s Jefferson River canyon supports a rich southwestern Montana wildlife community — mule deer (abundant on the canyon slopes, visible at dawn and dusk), white-tailed deer (in the riparian corridor along the Jefferson), pronghorn (on the adjacent open flats), golden eagles (nesting on the limestone cliffs and soaring over the canyon), Lewis’s woodpecker (a distinctive black-and-red woodpecker associated with the ponderosa pine slopes of the Jefferson River canyon — look for it in the open pines near the trailheads), mountain bluebirds, western meadowlarks, yellow-breasted chats and other riparian songbirds. The cave itself supports a hibernating bat colony (several species of bats use the cavern for winter hibernation — do not disturb bat hibernation areas; white-nose syndrome is a critical bat conservation concern throughout Montana).

Lewis and Clark Caverns State Park preserves a significant section of the Jefferson River canyon ecosystem — one of the most intact river-canyon habitats in southwestern Montana, with ponderosa pine and Rocky Mountain juniper on the dry south-facing slopes, riparian cottonwood and willow along the Jefferson, and limestone-specialist plant communities on the cliff faces. The cave’s bat colony (hibernating in winter; foraging in summer) provides important insect-control ecosystem services for the surrounding agricultural land. White-nose syndrome (a fungal disease that has devastated bat populations across North America) is a critical conservation concern; the park follows strict protocols (no personal gear brought into the cave; guided-tour-only access) to minimize disease spread. The Madison Limestone cliff ecosystems support rare plant communities unique to calcareous substrates.

Lewis and Clark Caverns holds a treasured place among Montana’s natural icons — Montana’s first state park (established 1937), the finest limestone cavern in the Pacific Northwest, a landmark of the Lewis and Clark Trail corridor (the Jefferson River valley was the Corps of Discovery’s route through southwestern Montana), and a landscape of extraordinary geological beauty in one of the most scenic river canyons in the northern Rockies. For visitors making the I-90 corridor through southwestern Montana, Lewis and Clark Caverns is the finest single detour from the highway — an underground geological world that rewards the 2-hour guided tour with an experience found nowhere else in Montana. The caverns are a cherished geological and cultural icon of southwestern Montana.

Lewis and Clark Caverns State Park is on MT-2, approximately 19 miles west of Three Forks and 30 miles east of Whitehall in Jefferson County. The park is about 50 miles west of Bozeman via I-90 west (exit at Cardwell or Three Forks). Bozeman has full resort services; Three Forks and Whitehall have basic services. A Montana state park entrance fee applies; cave tour tickets are sold separately (book in advance at FWP for summer weekend tours, which fill quickly). Tours operate May through September; check FWP for current tour schedules, prices and availability. The park campground (electric and tent sites) is available May through September — reserve at FWP. Check FWP for current hours and conditions before visiting.

Montana Fish, Wildlife & Parks manages Lewis and Clark Caverns. Bat conservation is the most critical issue — the park’s hibernating bat colony is vulnerable to white-nose syndrome; the guided-tour-only policy (no independent caving) minimizes disturbance to hibernating bats and reduces the risk of WNS introduction. Never enter the cave except with a guided FWP tour. The cave’s speleothems are irreplaceable — never touch any stalactite, stalagmite or flowstone surface (hand oils and physical contact can permanently alter or destroy the formations, which took thousands of years to develop). Stay with your guide at all times in the cave. On the surface, stay on designated trails and do not disturb the limestone cliff plant communities. Report any unusual bat mortality or behavior to FWP staff.

The cave tour involves 600+ steps, some passages requiring ducking and careful footing in narrow sections — wear sturdy, closed-toe shoes with good traction (absolutely no flip-flops or sandals; the cave floor can be wet and slippery); the tour is not recommended for visitors with serious mobility limitations. The cave is 48°F year-round — bring a fleece or light jacket even in summer. Claustrophobic visitors should be aware that some passages are narrow; ask the guide about the route before committing. On the surface trails, rattlesnakes are present on the dry, rocky slopes above the Jefferson River — wear boots and watch where you step. The Jefferson River offers fishing but is a cold, swift mountain river; wear a PFD if boating. Respect the cave’s physical demands, the rattlesnakes on the surface and the river current.

Montana state park entrance fee (check FWP). Cave tour ticket required; book in advance at FWP for summer weekends. No independent caving (guided tours only). Do not touch any cave formations. Photography is permitted in the cave (no flash on formations; check guide’s instructions). Pets are not allowed on the cave tour or in the cave area (pets are welcome on surface trails on leash). Camping: reserve at FWP; check campground fees and availability. Fires in designated fire rings only; check FWP for current fire restrictions. Pack out all trash. Check FWP for current tour schedule, prices and any special regulations before visiting.

Three Forks, Montana (19 miles east — the confluence of the Jefferson, Madison and Gallatin rivers that Lewis and Clark named in 1805; the Missouri Headwaters State Park at Three Forks is one of the most historically significant Lewis and Clark sites in Montana), the Madison River canyon (30 miles east via US-287 — one of the premier fly-fishing rivers in the world, with the Bear Trap Canyon Wilderness Area), Bozeman (50 miles east — Montana’s most vibrant mountain city, with the Museum of the Rockies — the finest dinosaur museum in North America — and a superb restaurant and outdoor-gear scene), the Tobacco Root Mountains (visible to the south from the park), and the Jefferson River corridor (a beautiful, uncrowded river valley with excellent fishing and wildlife) define the region.

Book the cave tour online at FWP as far in advance as possible for summer weekends — the 5-6 daily departures sell out weeks ahead in July and August. Bring a fleece or light jacket in your daypack (the cave is 48°F regardless of the outside temperature; the contrast between a 95°F summer day outside and the cave interior is striking). After the cave tour, hike the Jefferson River Overlook Trail (1.5 miles round trip to a panoramic view of the Jefferson River canyon, the Tobacco Root Mountains and the broad southwestern Montana valley) for the full park experience above ground. The combination of the Lewis and Clark Caverns cave tour and a stop at Missouri Headwaters State Park in Three Forks (the most significant Lewis and Clark historic site in southwestern Montana) makes the finest single day trip from Bozeman in the region.