The development of transportation in Colorado is a story of high courage and eventful daring. More than half of its terrain is rough and mountainous, but builders of railroads and highways have blasted and tunneled their way across this wilderness of peaks and canyons into the remotest sections of the State. Remarkable engineering feats have attended this work at every step—Hanging Bridge in the Royal Gorge, by which tracks are suspended above the roaring waters of the Arkansas River; the Carleton Tunnel, the Moffat Tunnel, and the Trail Ridge Road.

The first routes of the white man into and across the State naturally followed the trails and passes used for centuries by the Indians. Such was the branch of the Overland Trail up the South Platte River; such, too, was the Mountain Division of the Santa Fe Trail, which left the Arkansas River at Fort Bent and struck southwestward through what is now Trinidad to enter New Mexico over Raton Pass; the Ute Pass Trail along the northern base of Pikes Peak into South Park was named for the Indians who habitually used it. The watercourse routes provided practicable avenues of travel and assured wayfarers of fuel, water, and forage. During the feverish gold rush of 1859, however, fortune-hunters were willing to face almost any danger and endure any hardship if only they could make better speed, and they blazed a more direct but more hazardous route, the Smoky Hill Trail, which followed the Smoky Hill River through west central Kansas and proceeded across the high dry plains to Denver, a route roughly paralleled by present highway US 40. These early trails were little more than many pairs of ruts made by the wheels of heavy wagons. When a pair had been worn too deep for use, wagons straddled the old ruts and created new ones. On the prairies of eastern Colorado the grass-grown scars of these emigrant and trade routes are still to be seen here and there. In addition to rough roads, early travelers faced the hazards of bogs and swollen rivers, as well as the danger of attack by Indians and outlaws.

One of the earliest vehicles used by trappers and traders was the two-wheeled Red River cart, ordinarily used in conjunction with trains of pack mules. As trade developed with New Mexico, the cumbersome Spanish caretta with its two great wooden wheels came creaking along the Santa Fe Trail. The ox-drawn prairie schooner characterized the gold rush period, although in the feverish year of 1859 every kind of burden-bearing animal and conveyance was pressed into service. In their anxiety to reach the new Eldorado many gold-hunters started on foot in patent-leather boots and high stove-pipe hats, with merely the supplies that could be carried in a carpetbag or wheelbarrow. Many of the disappointed prospectors attempted to return to “America” by navigating the South Platte, ventures that usually ended in disaster.

Transportation companies were soon organized to serve the gold fields; one of the first was the Leavenworth and Pikes Peak Express, which in 1859 began carrying mail and freight from the Missouri River to Denver and Auraria. Five years later the Butterfield Overland Dispatch, better known as the B. O. D., inaugurated a fast freight and passenger line along the Smoky Hill route. In 1866 the Wells Fargo Company acquired both lines. Until supplanted by railroads and motor buses, the stagecoach lines were extended to serve even the most isolated communities. On some of the crude mountain roads grades were so steep that the drivers had to drag huge logs as brakes, and travel was literally hair-raising.

From the first, Coloradoans were aware of the transportation handicap imposed by the Rockies and bent every effort to have a transcontinental railroad constructed through the State. They sponsored costly surveys in an attempt to persuade Union Pacific officials to build their line through the mountains west from Denver, but the easy grade of Sherman Hill in Wyoming proved more persuasive. The first railroad in the State, completed in June 1870, linked Denver with the Union Pacific at Cheyenne. Connections with Kansas City and St. Louis were established later that year with the completion of the Kansas Pacific Railroad, now part of the Union Pacific System.

In 1871, General William J. Palmer and his associates began construction of the Denver & Rio Grande, a daring and elaborately conceived system. The D. & R. G. reached Pueblo the following summer and pushed westward up the Arkansas to Florence. In February 1878 the Santa Fe Railway, which had entered Colorado along the Arkansas Valley from the east, outwitted Palmer and secured control of Raton Pass on the route southward into New Mexico. Two months later, however, the Denver & Rio Grande won a spectacular war with the Santa Fe for possession of the right-of-way through the Royal Gorge of the Arkansas, which enabled it to push on and across the Continental Divide at Marshall Pass (10,856 alt.), then and now the highest transcontinental railroad traverse in North America; this narrow-gauge line was completed to Utah late in 1882. By July 1880, rails had been laid north to Leadville, but the Rio Grande's standard gauge main line from Denver to Ogden over Tennessee Pass was not completed until 1890. Many of the independent local railroads constructed during this early period have since been abandoned or absorbed by the seven major trunk lines entering the State.

Denver's recurring dream of a transcontinental railroad seemed to be on the point of fulfillment in 1902 when David H. Moffat and associates built the Denver, Pacific & Northwestern Railway, later renamed the Denver & Salt Lake (Moffat) Railway, financed with local capital. Moffat and his partners sank their fortunes in the venture but could not proceed with construction beyond Craig, Colorado. The construction of the Moffat Tunnel (1922-27), built with public funds, and the completion in 1934 of the Dotsero Cutoff, linking the Denver & Salt Lake with the main line of the Denver & Rio Grande, placed Denver for the first time directly on a main transcontinental route.

The early railroads in the mountains were narrow gauge. Light rails laid three feet apart carried small but powerful locomotives drawing freight cars and passenger coaches of proportionate size. The Denver & Rio Grande, first to employ the narrow gauge, was dubbed the "baby railroad," but its diminutive trains were soon winding their way up narrow canyons into almost inaccessible districts. A narrow gauge line, it was said, "could curve on the brim of a sombrero," and in many places virtually had to do so; the early boom camps were served almost exclusively by such narrow gauge systems. While the most important trunk lines have long since been converted into standard gauge, hundreds of miles of "baby railroad" remain in Colorado.

No history of transportation in Colorado should overlook the homely and unromantic burro. In the great days of mining, pack trains of burros wound up difficult trails in single file, carrying supplies to shafts and tunnels, returning with heavy loads of ore. Sturdy and tireless, as sure-footed as a mountain goat, the "Rocky Mountain Canary," as he was known for his raucous bray, made a place for himself in the hearts of lonely prospectors as an invaluable helper and steadfast friend who never deserted, no matter how hard the going.

Electric railways have played a prominent part in the transportation service of Colorado. For many years Cripple Creek had electric railway connections with Victor, Goldfield, Altman, and other neighboring camps. Electric trolleys were early operating in Colorado Springs, Pueblo, and Denver. Local buses now supplement such service. On August 1, 1920, the tramway employees in Denver struck for higher wages and more satisfactory working conditions, and seven persons were killed in subsequent hostilities between strikers and company guards (see Denver).

With the establishment of the first mining camps, Colorado found itself in need of good roads, but the building of a comprehensive highway system proved to be a Herculean task. In Territorial days and during the early years of statehood public funds were not available for this purpose, which stimulated the construction of rough toll roads. The advent of the automobile and truck made the problem of building and maintaining good roads even more acute. Broad highways were at length constructed across the plains and over the Continental Divide into the western mesa country, uniting all parts of Colorado. The cost of maintaining thousands of miles of mountain highways, which have to be kept free of snow in winter months, has proved an enormous burden to the State.

With a network of hard-surfaced roads uniting every section of Colorado, trucking has grown in importance; this type of transportation now competes with the railroads in short-haul freighting, particularly of livestock and farm produce, for trucks can be loaded at ranch or farm and be driven directly to their destination. And the bus, modern counterpart of the stagecoach, speeds smoothly and swiftly over paved or graveled highways to penetrate the farthermost corners of Colorado.

Air traffic, as a form of transportation, has been considerably retarded by the physical character of the State. Good airports in the mountainous areas are few, and mountain flying is still extremely hazardous. Since 1937, however, Denver has been served by a direct transcontinental air mail and passenger route. In gold rush days, when there was a cry for speed and yet more speed, coaches on the express stage lines carried eager fortune-hunters from the Missouri River towns to Denver in ten days. Now huge metal airliners, with double the capacity of the trim wood-and-canvas coaches, travel the distance in less than half that number of hours.

The State's transportation system is the foundation of its largest and most profitable "industry," tourist travel, which contributes an estimated gross income of $100,000,000 a year. The several transportation and communication services regularly employ some 35,000 Coloradoans, adding many thousands more during the summer tourist season.