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Mastodon State Historic Site is a Missouri state park located in Imperial, Jefferson County, Missouri — not Illinois, despite occasional confusion due to its proximity to the Illinois border. It preserves the Kimmswick Bone Bed, one of the most significant Pleistocene fossil sites in North America, where the bones of American mastodons and other Ice Age animals have been excavated since the early 19th century.
The site gained international scientific attention in 1979 when archaeologists confirmed co-occurrence of Clovis culture artifacts alongside mastodon remains, providing some of the earliest direct evidence of humans and mastodons occupying the same landscape in North America. That discovery made Kimmswick not just a paleontological site but an archaeological one of lasting importance.
Today, the site is managed by Missouri State Parks and includes an interpretive museum, walking trails through wooded terrain, and preserved excavation areas. It functions as both an educational destination for families and school groups and a place of genuine scientific significance for those interested in prehistoric natural history.
Before You Go
Check Current Hours and Admission
Opening hours and admission fees are set by Missouri State Parks and can change seasonally or due to staffing. Always verify current details on the official Missouri State Parks website or by calling the site directly before your visit.
What to Bring
- Comfortable walking shoes suitable for light trail terrain
- Water bottle, especially for warm-weather visits
- Sunscreen and insect repellent during summer months
- A camera — the museum exhibits and wooded trails photograph well
Accessibility
The museum building is generally accessible, but parts of the outdoor trail network can be uneven. Contact the site in advance if you have specific mobility requirements to confirm current accessibility conditions.
Group and School Visits
The site is a popular destination for school field trips. If visiting with a large group, contact the site ahead of time to coordinate and check whether guided programs are available on your preferred date.
Getting There
Mastodon State Historic Site is located off Interstate 55 in Imperial, Missouri, roughly 20 miles south of downtown St. Louis. It is most practically reached by private vehicle. From I-55, follow signs toward Imperial/Kimmswick and look for the marked park entrance on Seckman Road — verify the exact route via a current mapping application before departure.
The nearest major airport is St. Louis Lambert International Airport (STL), from which the drive to Imperial typically takes 30 to 45 minutes depending on traffic. No scheduled public transit serves the site directly. Rideshare services from the St. Louis metro area are a possible alternative, though availability in Imperial itself may be limited — confirm pickup options before relying on this.
Parking is available on-site and is free as of last known information, though this should be verified locally.
Things to See & Do
Museum and Exhibits
The on-site museum is the centerpiece of any visit. It houses fossil specimens including mastodon bones and teeth recovered from the Kimmswick Bone Bed, interpretive displays on Ice Age ecology, and exhibits explaining how the Clovis archaeological evidence was identified. The museum is designed to be accessible to general visitors while providing enough scientific context to satisfy those with a deeper interest in paleontology or archaeology.
Walking Trails
Several nature trails wind through the wooded property, passing near the original excavation areas. Interpretive signage along the trails contextualizes what was found and where. The terrain is relatively gentle and suitable for most fitness levels, though trail conditions can be muddy after rain.
Fossil Dig Programs
At certain times of year, the site offers structured programs — sometimes including junior paleontologist activities for children — where visitors can engage more actively with the site's scientific legacy. Check the Missouri State Parks events calendar to see whether any programs coincide with your visit.
Photography and Nature Observation
Beyond the fossil history, the wooded grounds support local bird and wildlife populations, making the trails pleasant for casual nature observation even outside of museum hours.
Food & Drink
There are no food or beverage facilities within Mastodon State Historic Site itself. Visitors should plan to eat before arriving or bring their own snacks and water.
The nearby town of Kimmswick, just a short drive north, is a small historic community with a handful of restaurants, bakeries, and tea rooms that have historically served visitors to the area. Options and hours in Kimmswick are limited, so check ahead before counting on a meal there. The city of Arnold and the broader I-55 corridor offer more conventional dining options including national chain restaurants within a short drive of the site.
Practical Information
Emergency Services
In any emergency, call 911. Jefferson County has standard emergency response infrastructure. The nearest hospitals are located in the broader St. Louis metro area — confirm the nearest facility with your accommodation or via a local map before your visit.
Mobile Coverage
Mobile phone coverage at the site is generally adequate given its suburban-adjacent location, but signal can be inconsistent on the wooded trail network. Download offline maps of the area before arriving.
Visitor Tips
- The site can be busy on weekend mornings, particularly when school programs are running
- There is no ATM on site — carry cash or cards for any admissions or purchases
- Pets may be permitted on outdoor areas but verify the current policy with site staff, as rules may apply regarding leashes
- All fossil material is protected — collecting or removing any natural or archaeological material from the site is illegal
Safety
Mastodon State Historic Site is a safe, family-friendly destination within a low-crime suburban area of Jefferson County. Standard precautions apply: secure valuables in your vehicle, stay on marked trails, and supervise children near any excavation areas or uneven terrain.
The wooded trails can be slippery after rain and during winter months. Ticks are present in the area during warmer months — check yourself and children after walking the trails and wear appropriate clothing if visiting in summer. No significant wildlife hazards are associated with the site.
