Grand Canyon National ParkArizona 1 of 11
The views and the trail system at the Grand Canyon are hard to match. As Rodriguez says, the Grand Canyon has "very runnable terrain and it is spectacular at sunrise and sunset. Nothing like it." The trail is clearly established to prevent getting lost. If you are a seasoned trail runner ready for an extreme challenge, do the rim-to-rim (R2R) run, roughly 21 miles depending on your route; or the rim-to-rim-to-rim (R2R2R) run of about 40 tough miles.
Zion National ParkUtah 2 of 11
There are enough hills and climbing at this park to really test you, and the elevation never drops below 3,500 feet. The signature trail is a difficult 2.5-mile ascent to Angels Landing, which provides for the most stunning view of the park. Easier trails, like the Pa'rus Trail, are also available. For the hardcore runner, the Zion Traverse is a 48-mile route from one edge of the park to the other.
Yosemite National ParkCalifornia 3 of 11
Truly one of America's iconic landscapes, Yosemite is big enough to make your running experience whatever you want it to be. There are easy trails in Yosemite Valley and challenging trails in the High Sierras. In all, there are 750 miles of trails in the park, visiting places like Hetch Hetchy, the Mariposa Grove of giant sequoias, the park's iconic waterfalls, and more. Says Rodriguez: "You can either go tough and super challenging, or extremely flat and easy. It's a great place if you want to be in nature, but not too far from the amenities in the valley."
Denali National ParkAlaska 4 of 11
Denali is enormous, about the size of Massachusetts. There are plenty of established trails (mostly around the visitor center) like the 8.6-mile Triple Lakes Trail or the rugged 4.5-mile Mt. Healy Overlook Trail. "There's a very high likelihood of spotting wildlife," says Rodriguez, who loved the remoteness of her runs there. Moose, caribou and bears are all over the park.
Redwoods National ParkCalifornia 5 of 11
The 350-foot tall trees will give you a great perspective while you're running—you are just a small part of a big, big world. Rodriguez loves the well-marked, scenic trails throughout the park, as well as the lush forest that surrounds those routes. "It feels like a scene from Jurassic Park," she says. There are more than 200 miles of trails at the park, ranging from sea level to 3,000 feet above.
Rocky Mountain National ParkColorado 6 of 11
There's no better national park to satisfy your need for the mountains. Rocky Mountain has more than 60 peaks that exceed 12,000 feet, many of which have trails to the top. You could also jump onto the famous Continental Divide National Scenic Trail. For something flatter, try the Mill Creek Basin Trail on the park's east side. With more than 300 miles of trails in the park, your trail running can be what you make of it.
Acadia National ParkMaine 7 of 11
This park, along Maine's rugged coastline, has 45 miles of old carriage roads with a crushed rock surface for runners to explore. If you need a mountain fix, head up the 1,528-foot Cadillac Mountain using either the 4.5-mile North Ridge trail or the 7-mile South Ridge trail.
Yellowstone National ParkWyoming 8 of 11
In all, more than 1,100 miles of trails canvas this park. Take the Lone Star Geyser trail to see one of Yellowstone's many geothermal wonders, or touch the sky with a trek to the top of 10,969-foot Electric Peak. Either way, trail running in Yellowstone requires caution due to grizzly bears. Carry bear spray and make plenty of noise while you run. You don't want to run into a surprised mama bear.
Channel Islands National ParkCalifornia 9 of 11
No park better combines rugged trails with panoramic ocean views. Though you need to get to the islands by boat or plane, the trails once you get there are worth it. We suggest going to Santa Cruz Island, where enough miles and enough terrain are available for any type of run. There are also trail running races, like the Santa Cruz Island Eco-Extreme Trail Half Marathon each October.
Great Smoky Mountains National ParkTennessee 10 of 11
More than 150 hiking trails exceeding 800 miles gives trail runners a crazy number of options. The Cades Cove area is among the most popular; the area has an abundance of wildlife and has trails up to Thunderhead Mountain and Rocky Top. There's also an 11-mile road that circles the cove. You can take the Laurel Falls Trail to see a 90-foot waterfall, or jump onto the famed Appalachian Trail. The options are seemingly endless.