Glenwood Canyon

Glenwood Canyon, on I-70 between Glenwood Springs and Dotsero in west-central Colorado, is one of the most spectacular highway corridors in North America — a 12-mile-long gorge where the Colorado River has cut 2,000 feet into the White River Plateau limestone, creating sheer canyon walls of dramatic Paleozoic rock sequence rising directly from the river, with Interstate 70 following the canyon floor in an engineering marvel (the roadway is cantilevered, tunneled and bridged through the sheer canyon in a construction project that took 12 years and $490 million to complete).

The canyon also offers the Glenwood Canyon Recreation Trail (one of the finest paved cycling and walking trails in Colorado, running 16 miles through the canyon along the river), access to Hanging Lake (a spectacular travertine lake and waterfall reached by a 3-mile round-trip hike up Deadhorse Creek) and the Glenwood Hot Springs Pool (one of the world’s largest outdoor hot springs pools, in the town of Glenwood Springs at the canyon’s western end). Glenwood Canyon is a treasured natural and engineering icon of Colorado.

Spring (May through June) and fall (September through October) are the finest seasons for the cycling trail — the river is at high, roaring flow in May and June (snowmelt; visually dramatic), the canyon walls are lit spectacularly in the horizontal spring and fall light, and the temperatures are comfortable. Summer (July through August) is excellent but the canyon can be extremely hot (90-95°F at the river level) — cycle the trail early in the morning. The Hanging Lake permit system operates in peak season (May through September); the hike is extraordinary year-round but winter (ice on the trail) requires traction devices. Fall for the canyon cycling and the fall color of the cottonwoods along the river, and spring for the high river flow, are the highlights.

Glenwood Canyon has been a significant corridor since prehistoric times — the Ute people traveled through the canyon along the Colorado River before European contact. The Denver and Rio Grande Railroad built through the canyon in the 1880s (an engineering feat of its era), following the river grade through the sheer limestone walls. The construction of I-70 through Glenwood Canyon (1980-1992) was one of the most technically challenging highway construction projects in American history — the roadway includes tunnels bored through limestone walls, reversible lanes on a cantilevered section above the river, and no fewer than 40 bridges and 12 miles of retaining walls in a canyon where there was no room for a standard roadway; the project won engineering design awards. The Glenwood Hot Springs have been used by the Ute people for centuries and have been a commercial resort destination since the 1880s.

Glenwood Canyon exposes one of the most complete Paleozoic rock sequences in Colorado — the Colorado River has cut through approximately 2,000 feet of Cambrian through Pennsylvanian age limestone, dolomite and sandstone, exposing rocks from 500-300 million years old in the canyon walls. The most dramatic geological feature is the Leadville Limestone (Mississippian, approximately 345 million years old) — a massive gray limestone sequence forming the steepest and highest cliff faces in the canyon. Above the Leadville are the colorful Pennsylvanian Maroon Formation (the same red-bed sequence visible in the Maroon Bells area) and the Mesaverde Group. The canyon’s sheer walls and the river’s rapid down-cutting reflect the rapid uplift of the White River Plateau (a structural dome) in the Tertiary period. The Paleozoic limestone sequence, the structural uplift and the Colorado River incision created Glenwood Canyon.

Glenwood Canyon’s river corridor and canyon-wall habitat support canyon wildlife — Canada geese and mallards on the Colorado River, common mergansers (fishing the clear river), belted kingfishers, canyon wrens (singing from the limestone walls), American dippers (walking underwater in the river to feed on invertebrates — one of the most charming bird behaviors in the Rockies), mule deer on the canyon slopes, black bears and mountain lions (present but rarely seen), bighorn sheep (occasionally visible on the steep upper canyon slopes), and peregrine falcons (nesting on the limestone cliff faces in spring). The river is an important corridor for wildlife movement through the canyon.

Glenwood Canyon’s Colorado River ecosystem is a critical river corridor in the Colorado watershed — the canyon serves as a wildlife movement corridor between the White River Plateau and the Flat Tops Wilderness to the north and the Maroon Bells-Snowmass Wilderness to the south. The Colorado River in the canyon (above the Shoshone Power Plant diversion) supports a native-fish community including the endangered Colorado pikeminnow and other Colorado River native species. The canyon’s recreational trail and highway co-exist in a narrow corridor; minimizing vehicle and recreational disturbance to the river-corridor wildlife (particularly during the spring raptor nesting season) is a management priority.

Glenwood Canyon holds a treasured place among the natural and engineering icons of Colorado — one of the most spectacular natural canyon drives in North America, a world-class cycling trail destination, the access corridor to Hanging Lake (one of Colorado’s most photographed destinations), and the gateway to Glenwood Springs (Colorado’s premier hot-spring destination). The I-70 highway engineering achievement (12 years, $490 million, one of the most complex roadway construction projects in American history) is itself a landmark of American civil engineering. Glenwood Canyon is a cherished natural and cultural icon of Colorado.

Glenwood Canyon is accessible from I-70 between Glenwood Springs (exit 116) and Dotsero (exit 133). The canyon has several parking areas and trailheads along the highway (Grizzly Creek Rest Area, Hanging Lake Trailhead at exit 125, No Name rest area). The Glenwood Canyon Recreation Trail can be accessed from the Grizzly Creek Rest Area and from Glenwood Springs. Glenwood Springs (at the west end) has full resort services (hotels, restaurants, the hot springs pool, gear shops, and bike rentals). Grand Junction is 80 miles west; Vail is 40 miles east. The Hanging Lake hike requires a permit in peak season (May-September; reserve at recreation.gov).

The Colorado Department of Transportation manages the I-70 corridor; the Hanging Lake trail is managed by the White River National Forest. Hanging Lake is the most critical conservation feature — the travertine lake and its fragile ecosystem are easily damaged by foot traffic; the permit system (limited to 615 visitors per day) protects the lake from the overcrowding that was damaging it before permits were instituted. Hanging Lake itself: do not enter the water (swimming is prohibited; the travertine formations are destroyed by contact with body oils and sunscreen). Stay on the designated trail; do not pick flowers or break off travertine. The canyon trail is a no-smoking trail. Pack out all trash.

Hanging Lake trail: the 3-mile round-trip hike gains 1,000 feet on a rocky, sometimes steep and wet trail; wear appropriate footwear (hiking shoes or boots with ankle support; the trail is slippery when wet from waterfall spray). The trail is very crowded in peak season (the permit system limits this; the trail’s steepness and length mean some visitors underestimate the fitness required). The Colorado River below I-70 is a significant kayaking and rafting corridor — carry skills and experience for the class III-IV rapids. The canyon’s geology makes it susceptible to rockfall during periods of freeze-thaw; the CDOT monitors rockfall risk and sometimes closes the canyon (check conditions before driving). Respect the trail fitness requirement, the river rapids and the rockfall monitoring.

Hanging Lake: permit required May-September (reserve at recreation.gov; limited to 615 visitors/day; fill quickly for weekend dates — reserve 2+ weeks in advance). No swimming in Hanging Lake (prohibited; fine). Stay on designated trail to and at the lake. Glenwood Canyon Recreation Trail: free; no permit required. I-70 may close in extreme weather or rockfall events (check CDOT for current conditions). Glenwood Hot Springs Pool: admission fee (check glenwoodnhotsprings.com). Pets on leash on the recreation trail; pets not allowed on the Hanging Lake trail. Pack out all trash.

Glenwood Springs (at the canyon’s west end — a full resort town with the Glenwood Hot Springs Pool, Vapor Caves, Sunlight Mountain Resort, excellent restaurants and a charming historic downtown — Doc Holliday is buried in the local cemetery), Aspen and the Maroon Bells (45 miles southeast via CO-82 — one of the finest mountain drives in Colorado), Vail (40 miles east on I-70 — one of the world’s premier ski resorts), Rifle Falls State Park (25 miles west — a triple waterfall in a limestone canyon, the finest waterfall day trip from Glenwood Springs), and the Colorado River (the kayaking and rafting corridor through the canyon) define the region. Glenwood Canyon anchors the I-70 mountain corridor experience between Vail and Grand Junction.

Cycle the Glenwood Canyon Recreation Trail from Glenwood Springs east to the Grizzly Creek rest area (about 10 miles one-way; rent a bike in Glenwood Springs and take the Greyhound shuttle back — the shuttle runs in summer) for the finest no-car canyon experience; the 2,000-foot limestone walls overhead and the roaring Colorado River below are extraordinary from the trail level. Book the Hanging Lake permit at recreation.gov the moment your desired date opens (2-3 weeks before your visit for weekdays; months before for summer weekends — they disappear in hours). Soak in the Glenwood Hot Springs Pool at the end of the day — the world’s largest outdoor hot springs pool, at 90-93°F, is one of the finest post-adventure recoveries in Colorado.