The Rocky Mountain Arsenal National Wildlife Refuge is one of the best-kept secrets near Denver, partly because its name sounds like anything but a nature preserve. Its rolling shortgrass prairie, lakes and cottonwood groves sit between Commerce City and Denver International Airport. Bison, mule deer, white-tailed deer, coyotes, prairie dogs and many birds of prey live here, and on a clear day the Front Range lines the western horizon behind them.
From arsenal to refuge
The land has a dramatic history. During World War II the U.S. Army built a plant here to manufacture chemical weapons, and after the war parts of the site were leased to private companies that produced agricultural chemicals. The result was serious contamination. Over the following decades, a major environmental cleanup took place under federal oversight. Wildlife, meanwhile, had quietly thrived in the buffer lands around the industrial core; the discovery of a winter roost of bald eagles helped spark the effort to protect the area. Congress designated the site as a national wildlife refuge, and as cleanup was completed in stages, more of it opened to the public. The visitor center tells the full story, including the cleanup itself.
The wildlife drive
The refuge's signature experience is its 11-mile self-guided wildlife drive, which the U.S. Fish and Wildlife Service estimates takes 45 minutes to an hour. The posted speed limit is 30 miles per hour, and slower is better for spotting animals.
- Bison areaPart of the drive becomes a one-way road through bison pasture, and you must stay in your vehicle there.
- Best lightEarly morning and the hour before closing bring the most activity and the best photos.
- BringBinoculars, a long lens if you have one, water and patience.
- Stay on routeLeaving the designated roads and trails is not allowed.
Bison are wild animals that can weigh as much as a small car and run faster than people. Never leave your vehicle in the bison area, never approach animals on foot elsewhere and give them the road if they choose to cross it.
Hiking and walking
Outside the bison pasture, the refuge has a network of walking trails, many of them flat and easy, around lakes, through prairie and past historic farm sites from the era before the arsenal. Trails near the visitor center make an easy introduction. Remember that you are in wildlife habitat: stay on marked trails, keep a respectful distance from animals and carry water, since shade is limited. The refuge's trail map shows current routes and any seasonal closures.
What you might see, season by season
| Season | Look for |
|---|---|
| Spring | Bison calves, songbirds returning, burrowing owls near prairie dog colonies |
| Summer | Active prairie dog towns, hawks overhead, deer at dawn and dusk |
| Fall | Deer rut activity, migrating waterfowl on the lakes, golden cottonwoods |
| Winter | Bald eagles and other raptors, bison against snow, fewer visitors |
Wildlife sightings depend on weather, time of day and luck. Refuge staff at the visitor center often know where animals have been seen recently.
Planning your visit
Hours
The U.S. Fish and Wildlife Service lists the refuge grounds as open from sunrise to sunset in fall, winter and spring, with extended hours to 8 p.m. from May 1 to August 1. The visitor center is open Wednesday through Sunday from 9 a.m. to 4 p.m. and closed on federal holidays, and the whole refuge closes on Thanksgiving, Christmas and New Year's Day. Hours can change, so check the official site before you go.
Getting there
The refuge sits about 10 miles northeast of downtown Denver. Drivers usually reach the main entrance in about 20 to 30 minutes, depending on traffic. Public transit does not serve the wildlife drive, so a car is the practical option.
Rules to know
- Pets are not allowed on the refuge, though they may ride along on the wildlife drive if they stay inside the vehicle.
- Feeding or approaching wildlife is prohibited.
- Stay on designated roads and trails.
- Fishing is allowed only in designated areas and seasons under refuge rules and with the required permits.
Pair it with
The refuge is a natural add-on to an airport day: it sits on the way between downtown and Denver International Airport, so a late-afternoon drive before an evening flight works well. See our airport to downtown guide for timing. Families can combine it with the kid-friendly ideas in the city, and wildlife lovers can continue to the bison herd at Genesee in the Denver Mountain Parks.
Frequently asked questions
Is the Rocky Mountain Arsenal free?
Yes. The U.S. Fish and Wildlife Service lists the refuge and its wildlife drive as free to visit.
Can you see bison at the Rocky Mountain Arsenal?
Yes. Bison are among the animals visitors commonly see from the wildlife drive. In the bison area the drive becomes a one-way road and visitors must stay in their vehicles.
What are the Rocky Mountain Arsenal hours?
The U.S. Fish and Wildlife Service lists the refuge grounds as open from sunrise to sunset in fall, winter and spring, and from sunrise to 8 p.m. from May 1 to August 1. The visitor center is open Wednesday through Sunday from 9 a.m. to 4 p.m. and closed federal holidays. The refuge closes on Thanksgiving, Christmas and New Year's Day.
Can I bring my dog to the Rocky Mountain Arsenal?
Pets are not allowed on the refuge, except that they may ride along on the wildlife drive if they stay inside the vehicle.
Sources
Checked against official sources in October 2026. Hours, fees, reservation rules and road status change often; the agency or venue linked above is always the final word. See how we research.