Standard gauge was favored for railway construction in the United States, although a fairly large narrow-gauge system developed in the Rocky Mountains of Colorado and Utah. Isolated narrow-gauge lines were built in many areas to minimize construction costs for industrial transport or resort access, and some of these lines offered common carrier service. Outside Colorado, these isolated lines evolved into regional narrow-gauge systems in Maine, New York, Pennsylvania, Ohio, Iowa, Hawaii, and Alaska. There was over 10,000 miles of narrow-gauge trackage built in the United States. By 1890, it was beginning to go out of favor, and by 1941, there were only about a dozen narrow-gauge railroads still operating.Moody, Linwood W. "Sunset on the Narrow Gauge," Railroad Magazine, pp. 6-33, August 1941, Vol. 30, No. 3, New York, New York.
New England
In New England, the first narrow-gauge common-carrier railroad was the Billerica and Bedford Railroad, which ran from North Billerica to Bedford in Middlesex County, Massachusetts from 1877 to 1878. There were extensive gauge lines in the Maine forests early in the 20th century. In addition to hauling timber, agricultural products and slate, the Maine lines also offered passenger services. The Boston, Revere Beach & Lynn Railroad was a narrow-gauge commuter railroad that operated in Massachusetts, much of whose right-of-way is used for rapid transit today. Narrow gauges also operated in the mountains of New Hampshire, on the islands of Nantucket and Martha's Vineyard and in a variety of other locations. The still-operating Edaville Railroad tourist heritage railroad in southeastern Massachusetts is a two-foot narrow-gauge system.
Mid-Atlantic
The last remaining gauge common carrier east of the Rocky Mountains was the East Broad Top Railroad in central Pennsylvania. Running from 1873 until 1956, it supplied coal to brick kilns and general freight to the towns it passed through, connecting to the Pennsylvania Railroad at Mount Union, Pennsylvania. Purchased for scrap by the Kovalchick Corporation when it ended common carrier service in 1956, it reopened as a tourist railroad in 1960. This line is the oldest surviving stretch of narrow-gauge track in the United States. Financial troubles would force the Kovalchick family to close the railroad following the 2011 season. The railroad sat dormant until 2020 when it was purchased and reopened by the EBT Foundation.
It was the last remnant of an extensive narrow-gauge network in New York and Pennsylvania that included many interconnecting lines. The largest concentration was in the Big Level region around Bradford, Pennsylvania, from which lines radiated towards Pittsburgh and into New York state. This group also included the Tonawanda Valley & Cuba Railroad. Though the TV&C's narrow-gauge tracks are long gone, the standard-gauge Arcade and Attica Railroad continues to run over a portion of the TV&C's route. The Waynesburg and Washington Railroad, a subsidiary of the Pennsylvania Railroad, operated in the southwestern part of the state until 1933.
The Philadelphia and Atlantic City Railway and the Pleasantville & Ocean City Railroad were originally built to gauge.
Southeast The Southeast helped initiate the narrow-gauge era. The first in Georgia was the Kingsboro & Cataula Railway, chartered in 1870. In Tennessee, the Duck River Valley Narrow Gauge Railway was also chartered in 1870, opening seven years later; it was converted to standard gauge in 1888. The first narrow-gauge railway in Alabama was the Tuskegee Railroad in 1871.
Longest lived of its narrow gauges was the East Tennessee and Western North Carolina Railroad. Originally built as a broad gauge in 1866, the line was later converted to a narrow-gauge railroad between Johnson City, Tennessee; Cranberry, North Carolina; and ultimately Boone, North Carolina. It continued in service until 1950.
Another long-lived southern narrow gauge was the Lawndale Railway and Industrial Co.
Midwest One of the first three narrow gauges in the U.S. – the Painesville & Youngstown – opened in Ohio in 1871, and the narrow-gauge movement reached its greatest length in the Midwest. For a brief time in the 1880s it was possible to travel by narrow gauge from Lake Erie across the Mississippi River and into Texas. The hub of this system, Delphos, Ohio, shared with Durango, Colorado the distinction of being the only towns in the United States from which it was possible to travel by narrow gauge in all four compass directions.
The Chicago Tunnel Company operated a long underground gauge freight railroad under the streets of the Chicago Loop. This common carrier railroad used electric traction, interchanged freight with all of the railroads serving Chicago, and offered direct connections to many loop businesses from 1906 to 1959.
Ohio was a center of the narrow-gauge movement. In addition to serving as the northern end of the Little Giant "transcontinental", it had several other notable lines, including the long-lived Ohio River & Western Railroad, the Kelley Island Lime & Transport Company (the world's largest operator of Shay locomotives, virtually all of them narrow gauge) and the Connotton Valley Railroad, a successful coal hauler still in operation today as the standard-gauge Wheeling & Lake Erie Railroad. Narrow gauge railroad mileage in Ohio reached its peak in 1883 and declined rapidly after 1884.
Numerous gauge common-carrier narrow-gauge lines were built in Iowa in the 19th century. The largest cluster of lines radiated from Des Moines, with the Des Moines, Osceola and Southern extending south to Cainsville, Missouri, the Des Moines North-Western extending northwest to Fonda and smaller lines extending north to Boone and Ames. These lines were all abandoned or regauged by 1900. The Burlington and Western and the Burlington and Northwestern system extended from Burlington to Washington, Iowa and the coal fields around Oskaloosa. This system was widened to standard gauge on June 29, 1902, and merged with the Chicago, Burlington and Quincy Railroad a year later. The Bellevue and Cascade, from Bellevue on the Mississippi to Cascade inland remained in service until abandonment in 1936. A caboose from the Bellevue and Cascade is the only surviving piece of Iowa narrow-gauge equipment. It currently operates on the Midwest Central Railroad in Mount Pleasant, a heritage railroad.
In 1882, thirty-two narrow-gauge logging railroads were constructed in Michigan, and by 1889 there were eighty-nine such logging railroads in operation, totaling almost of track.
Mountain West
At its peak, the mountain west region had a narrow gauge system which stretched from Montana to New Mexico; with the majority of routes operating out of central hubs in Colorado and Utah.
The Denver and Rio Grande Railroad, opened in 1871, was one of the earliest narrow gauge railroads in the United States and by far the longest and one of the most significant. The railroad's founder William Jackson Palmer during the early planning stages of the railroad in 1871 visited the Ffestiniog Railway in Wales while on his honeymoon, and while in the United Kingdom consulted with Scottish engineer Robert Francis Fairlie who convinced Palmer of the advantages of building the Rio Grande using narrow gauge.
The Rio Grande effectively circled the state of Colorado, and feeder lines were run to the mining communities of Leadville, Aspen, Cripple Creek, Telluride and Silverton. The Rio Grande would find itself in a railroad war with the Atchison, Topeka and Santa Fe Railway in 1878 from 1880 for control over the Royal Gorge canyon. The conflict would be settled by "The Treaty of Boston" in 1880, allowing the Rio Grande to continue building east towards Leadville and towards Grand Junction through the Black Canyon of the Gunnison. Through affiliated companies, the Rio Grande's lines would extended west to Ogden, Utah and south to Santa Fe, New Mexico.
The Rio Grande mainline was gradually re-gauged after it and the Colorado Midland Railway built a new standard gauge joint line to Grand Junction in 1890, but the southern portions remained steam-hauled and narrow gauge into the mid 20th century. This southern segment would be advertised as the "Narrow Gauge Circle" which via a connection with the Rio Grande Southern (which was among various narrow gauge railroads connecting with the larger Denver & Rio Grande which had been built by Otto Mears) allowed travelers to make a continuous journey through the southwestern corner of Colorado onboard narrow gauge trains. The cash strapped Rio Grande Southern would build a fleet of Galloping Goose cars to preserve the mail contract along their route from the 1930s until the lines abandonment in 1952.
As remaining segments of the Denver & Rio Grande Western's narrow gauge system were abandoned throughout Colorado in the mid-20th century, the San Juan Extension experienced a reprieve with the petroleum industry booming from the 1950s into the 1960s around Farmington, New Mexico. As traffic from the oil boom subsided, the Denver & Rio Grande Western abandoned the narrow gauge from Durango, Colorado to Chama, New Mexico; and the Chama to Antonito, Colorado portion of the line was jointly purchased by the states of Colorado and New Mexico to form the Cumbres and Toltec Scenic Railroad in 1970.
Tourism increased along the Silverton branch following World War II, and the area was popularized through Western films which frequently filmed along the San Juan Extension and the railroad became a popular road trip destination. Unable to abandon the Silverton branch, the D&RGW operated it as an isolated narrow gauge and steam powered route until 1981 when the line was sold and rebranded as the Durango and Silverton Narrow Gauge Railroad.
Operations of the Durango & Silverton and the Cumbres & Toltec have both been impacted by the ongoing Southwestern North American megadrought and fuel availability. The Durango & Silverton was closed by the Missionary Ridge Fire in 2002 marking the first time the railroad would be closed by fire danger in its history. In 2018 the railroad would close again due to the 416 Fire which was attributed to having been caused by the railroad, leading to a lawsuit against the railroad from the Federal Government to recoup fire fighting costs which would be settled with a $20 million fine against the Durango & Silverton. The Durango & Silverton would phase out coal fired steam locomotives, converting their steam locomotive fleet to burn oil to reduce embers, running their final coal fired train in early 2024. Both the Durango & Silverton and Cumbres & Toltec would purchase diesel locomotives from the White Pass and Yukon Route to provide alternative power to steam locomotives during high fire risk seasons and as emergency backups to traditional steam locomotives.
Other major narrow-gauge railroads in Colorado included the Denver, South Park and Pacific, the Colorado Central, and the Florence and Cripple Creek. The Uintah Railway operated in Utah and Colorado, and boasted the tightest curve (Moro Castle curve) on a US common carrier at Baxter Pass. Some short segments of narrow gauge railroads have been rebuilt in Colorado as heritage railroads with the Georgetown Loop Railroad opening in 1973 and the Como Roundhouse having been initially restored and expanded since 1984. The Colorado Railroad Museum established in 1959, operates a demonstration loop of narrow gauge track in Golden, Colorado.