Colorado's mountains belong to the Southern Rocky Mountains, a set of separate ranges that fill the western part of the state: the Front Range facing the plains, the Mosquito and Sawatch ranges in the centre, and the Elk, San Juan and Sangre de Cristo mountains farther south and west. Together they hold 53 summits above 14,000 feet (4,267 m) with at least 300 ft (91 m) of prominence, the "fourteeners", more than any other state; Alaska is second with 29. The highest is Mount Elbert in the Sawatch Range, 4,401 m (14,440 ft), which is also the highest point in the entire Rocky Mountains. The state is so high that even its lowest point, where the Arikaree River leaves for Kansas, sits at 1,011 m (3,317 ft), the highest low point of any US state. One road shows the heart of all this better than any list: US Highway 24, which climbs out of Colorado Springs over the Front Range, crosses South Park and the southern tip of the Mosquito Range, runs up the Arkansas valley past the two tallest peaks in the Rockies and ends at Interstate 70 in Minturn.
Ute Pass: Climbing Out of Colorado Springs Beneath Pikes Peak
US 24 leaves Colorado Springs at 1,839 m (6,035 ft) and heads straight into the Front Range, the first mountains a westbound traveller meets on leaving the Great Plains. The range runs from Casper, Wyoming, to Pueblo and rises nearly 3,000 m (10,000 ft) above the Great Plains. Its southern anchor is Pikes Peak, 4,302 m (14,115 ft), the easternmost fourteener in the United States and more than 2,400 m (8,000 ft) higher than downtown Colorado Springs.
The mountain is built of Pikes Peak granite, a pink rock coloured by potassium feldspar that crystallised as magma deep underground about 1.05 billion years ago. It was lifted to the surface much later, when the Laramide orogeny pushed up the Rockies between roughly 80 and 35 million years ago, and erosion stripped off the softer cover. Zebulon Pike tried and failed to climb it in November 1806; Edwin James reached the top on 15 July 1820. The view from the summit in 1893 led Katharine Lee Bates to write the poem that became "America the Beautiful", and since 1915 a 31 km (19 mile) toll road has climbed to the top from Cascade, a village the highway passes.
The route to the west is Ute Pass, a canyon the Ute people used to haul salt from South Park to Santa Fe and Taos. The road winds up Fountain Creek through Manitou Springs, Cascade, Green Mountain Falls and Woodland Park to its summit at Divide, 2,793 m (9,165 ft). The Colorado Midland Railway followed the same line from 1888 to reach the mining camps of Leadville and Aspen; the tracks were later removed once mining declined, and from Divide down to Colorado Springs the highway is now four lanes.
Wilkerson Pass and the Grassland Floor of South Park
Beyond Divide the road drops through forest and then crests Wilkerson Pass, 2,898 m (9,507 ft), on the eastern rim of South Park. From the summit the whole basin spreads out below: roughly 2,590 km² (1,000 sq mi) of open grassland between 2,700 and 3,000 m (9,000 and 10,000 ft) high, the largest and southernmost of Colorado's three high basins called "parks" (North Park and Middle Park lie farther north). It feeds the headwaters of the South Platte River.
A park, in Colorado usage, is a high, broad basin enclosed by mountains. Geologically, South Park is a broad faulted syncline, a downfold of Paleozoic and Mesozoic sediments trapped between the Precambrian granites of the Front Range on the east and the Sawatch uplift on the west. The extinct Thirty-Nine Mile volcanic field rises to the southeast. Pleistocene glaciation spread a thin layer of gravel over the floor. Placer gold was found in the valley's streams in 1859, and the gravel ridges east of Fairplay, left by dredging for gold, are still visible. Fairplay is the largest town in the basin, with 724 people at the 2020 census. On the western skyline stands the Mosquito Range, a 64 km (40 mile) wall whose high point, Mount Lincoln, reaches 4,354 m (14,286 ft).
Trout Creek Pass to Buena Vista and the Collegiate Peaks
US 24 slips around the southern end of the Mosquito Range at Trout Creek Pass, 2,849 m (9,346 ft), on the line between Park and Chaffee counties. Road cuts on the eastern approach expose Pennsylvanian black shale and grey limestone laid down before the Ancestral Rockies rose around 300 million years ago. The Denver, South Park and Pacific Railroad crossed here in 1879 to reach the silver boom at Leadville.
The descent on the west side is the most dramatic moment of the drive. The highway falls into the upper Arkansas River valley, and across it the Sawatch Range rises as a single wall. This valley is the northern end of the Rio Grande rift, a zone where the crust has been pulled apart for about 35 million years. The Mosquito and Sawatch ranges were once one uplift; rifting dropped the valley between them.
At Buena Vista, 2,428 m (7,965 ft), the road turns north up the valley beneath the Collegiate Peaks, a stretch of the Sawatch named because several summits honour universities: Mount Princeton, Mount Yale, Mount Columbia, Mount Harvard and Mount Oxford, with Mount Belford among their neighbours. Mount Princeton, 4,328 m (14,200 ft), climbs nearly 2,100 m (7,000 ft) from the valley floor in about 10 km (6 miles), and Mount Harvard, 4,396 m (14,421 ft), is the third-highest summit in the Rockies. The Arapaho called the group the Elk's Head. West of town, Cottonwood Pass carries a road over the range at 3,696 m (12,126 ft).
Leadville, Mount Elbert and Mount Massive
North of Buena Vista the highway climbs gently along the young Arkansas River, which rises in the snowfields of the Sawatch and Mosquito ranges and will run 2,364 km (1,469 miles) to the Mississippi. The valley ends at Leadville, 3,084 m (10,119 ft), the highest incorporated city in the United States. Placer gold found in California Gulch in 1859 and 1860 started the town's story. In 1874 miners realised that the heavy black sand clogging their sluices was cerussite, a silver-rich lead ore; silver-lead lodes followed, the town was founded in 1877, and by the late 19th century Leadville was the second-largest city in Colorado after Denver.
Two peaks dominate the skyline west of town. Mount Elbert, 4,401 m (14,440 ft), lies about 19 km (12 miles) southwest of Leadville above the village of Twin Lakes. It is the highest point in Colorado, the Rocky Mountains and the whole Mississippi basin, and second only to California's Mount Whitney in the contiguous states. Henry Stuckle of the Hayden Survey recorded the first ascent in 1874. Its standard trails need no climbing gear, which has earned it the nickname "gentle giant".
Mount Massive stands 8 km (5 miles) to the north-northwest and is just 12 ft (3.7 m) lower. It has five summits above 14,000 ft on a ridge more than 4.8 km (3 miles) long, giving it more area above that line than any other peak in the lower 48 states. The near-tie caused a feud after the Great Depression: supporters of Massive piled stones on its summit to make it taller, and Elbert's supporters knocked them down. The Sawatch as a whole holds 15 fourteeners along a range about 130 km (80 miles) long that forms part of the Continental Divide.
Tennessee Pass, the Continental Divide and Mount of the Holy Cross
Leaving Leadville, US 24 crosses the Continental Divide at Tennessee Pass, 3,177 m (10,424 ft), in a gap between the northern tips of the Sawatch and Mosquito ranges. It is the high point of the drive, yet the summit is nearly level. Rain falling on its south side runs down the Arkansas to the Gulf of Mexico; rain falling to the north runs into the Eagle River and on to the Colorado River and the Gulf of California. The Denver and Rio Grande railroad built a line over the pass in 1881 that became part of a main line; in recent decades it was the highest active main-line railroad pass in the United States, until the last revenue train crossed in 1997. During the Second World War, troops of the 10th Mountain Division trained for alpine warfare at Camp Hale in the valley just north, where about 15,000 soldiers were housed at the peak.
The last mountain on the route is Mount of the Holy Cross, 4,269 m (14,005 ft), the highest point of the northern Sawatch Range and of Eagle County. It stands in the Holy Cross Wilderness about 11 km (7 miles) west-southwest of Red Cliff, and US 24 passes near it at the old mining town of Gilman. A cross-shaped snowfield on its northeast face gives the peak its name. Ferdinand Hayden and the photographer William Henry Jackson made the first recorded ascent in 1873, Thomas Moran painted it and Henry Wadsworth Longfellow wrote a poem about it. Herbert Hoover declared it a national monument in 1929, but its remoteness kept visitors away, and the monument was abolished in 1950.
The road ends a short way on at Minturn, where it meets Interstate 70 in the Eagle River valley. Along the way it has crossed the Front Range, South Park, the Mosquito Range and the rift valley of the upper Arkansas, and run along the foot of the highest peaks in the Rockies. What it misses lies south and west: the volcanic San Juan Mountains, the Sangre de Cristo range above the San Luis Valley and the Elk Mountains around the Maroon Bells near Aspen. Those ranges, the plateaus beyond them and the plains to the east are covered in our guide to landforms in Colorado. The Front Range north of Pikes Peak continues in Rocky Mountain National Park, and the snow that melts off the western side of Tennessee Pass ends up in the Colorado River.