The line dates back to the early 1880s, when the predecessors of the D&RGW completed a narrow gauge line through the Royal Gorge, over Marshall Pass, through the Black Canyon of the Gunnison, across the Utah desert, and over Soldier Summit. It was rebuilt to standard gauge in 1890, and has since remained a through line, often serving as parts of larger networks including the Gould transcontinental system, Southern Pacific, and now the Union Pacific.
In the meantime, the Utah and Pleasant Valley Railway (U&PV) had built a line from the coal mines in the Pleasant Valley to Provo on the Union Pacific Railroad-controlled Utah Southern Railroad. The company was incorporated on December 11, 1875 under the general laws of Utah by owners of land in the valley. The company began grading in April 1877 and track laying on August 29, 1878, driving the last spike between Pleasant Valley and Springville on November 5, 1879. The short distance in the Utah Valley from Springville to the larger city of Provo, which closely paralleled the Utah Southern, opened in October 1880. Investor Charles W. Scofield of New York, who was already in control of two other mining roads - the Bingham Canon and Camp Floyd Rail Road since 1873 and the Wasatch and Jordan Valley Railroad since 1875 - acquired the U&PV in October 1878.
The U&PV began at a mine in the Pleasant Valley south of Scofield, heading north along the present Pleasant Valley Subdivision to the Scofield Reservoir. The old grade has been flooded until it leaves the lake to the north, rising to an elevation of above sea level before descending, via a pair of switchbacks, to Starvation Creek. The valley of that creek took the railroad to the Spanish Fork Canyon, and the later D&RGW, at Tucker. The remainder of the U&PV is now, for the most part, still operated, as it follows Spanish Fork Canyon into the Utah Valley.
Associates of Palmer incorporated the Sevier Valley Railway in Utah on December 7, 1880, with a route paralleling the Union Pacific's lines from the railroad center of Ogden south through Salt Lake City and Provo to Nephi, and then continuing through Salt Creek Canyon and the Sanpete Valley to Salina in the Sevier Valley. There it would split, one line continuing south to the Arizona state line, and the other turning east through Salina Canyon and across the Castle Valley to the Grand (Colorado) River, following it to meet the westward-building D&RG at the Colorado border. To counter this threat to its monopoly, the Union Pacific set up the Utah Southern and Castle Valley Railroad less than two weeks later to extend its Utah Southern through Salina Canyon to the Castle Valley. In another week, when UP workers reached the canyon, the Sevier Valley had already begun grading.
On May 26, 1881, D&RG interests incorporated the Salt Lake and Park City Railway, a branch from Salt Lake City east to Park City and Coalville. The lines of this company and the Sevier Valley were included in the far-reaching charter for the Denver and Rio Grande Western Railway, incorporated on July 21, 1881 and immediately consolidated with the others. Palmer knew that it would be important to first complete the line to Ogden, where the Central Pacific Railroad extended west to California. It was rumored as early as April 1881 that the D&RG had gained control of the U&PV and would bypass Salina Canyon, instead using a shorter route northwesterly from Castle Valley to a connection with that road, and Palmer confirmed this in September. (The original grading through Castle Valley was never used for a railroad, although in the 1910s it was briefly part of the Midland Trail, now US-6.) The D&RGW bought the assets of the Wasatch and Jordan Valley Railroad, which had merged with the Bingham Canon and Camp Floyd Rail Road, at foreclosure on December 31, 1881, adding to its system two profitable branches from Midvale to Bingham and Little Cottonwood Canyons.
The D&RGW similarly acquired the U&PV's property on June 14, 1882, and at about that time began operating trains between Salt Lake City and Pleasant Valley, using new trackage north of Provo. The D&RG of Colorado leased the D&RGW of Utah on August 1, allowing the former to operate the latter for a payment of 40% of gross receipts. The difficult double switchback on the original U&PV was bypassed by a new connection to the under-construction D&RGW at Colton on November 23, 1882, as well as the new line from Colton over Soldier Summit to Tucker. D&RG and D&RGW crews met at a point now known as Desert, west of Green River, on March 30, 1883, and trains began running between Denver and Salt Lake City several days later. (Although the D&RG built the line from the state line to Desert, it was owned by the D&RGW.) Final completion to Ogden in May was delayed for several days by the Union Pacific's refusal to let the D&RGW cross, but on May 19 the D&RGW was complete. Palmer soon resigned as D&RG president, since the directors were opposed to further expansion, but remained in control of the leased D&RGW.
The expansion resulted in a large debt that the D&RG was unable to pay the interest on. D&RGW president Palmer and D&RG president Frederick Lovejoy got into an argument over the management and payment of rental for the leased D&RGW. Unable to break the lease, Lovejoy ordered the tracks torn up at the state line in retaliation, costing both railroads the Chicago, Burlington and Quincy Railroad's through traffic. The D&RG entered receivership on July 12, 1884 and the D&RGW on August 12, with D&RGW superintendent W. H. Bancroft being appointed to the Utah company. The two companies resumed friendly relations, and after the D&RG reorganized on July 14, 1886, it terminated the lease of the D&RGW on July 31, giving the latter company significant amounts of rolling stock. Palmer returned to his position as D&RGW president, the company having been released from receivership.
Now independent, the D&RGW looked to the east, where the standard gauge Colorado Midland Railway was building west from Colorado Springs with the intent of entering Utah. Palmer realized that if he did not widen his gauge and cooperate with the Midland, he might soon have new competition. To raise the money to convert the line, which would require about of new railroad where the existing grade was too steep or curvy, he incorporated a new Rio Grande Western Railway. (Palmer had initially proposed the name "Utah and Colorado Railway" for the new company.) The State Line and Denver Railway was incorporated May 16, 1889 with the power to build east to Glenwood Springs, Colorado, then the terminus of the Midland. That same day, it was consolidated with the old Denver and Rio Grande Western Railway, with articles of incorporation filed in both states on June 24.
Construction began immediately, the line being converted from Ogden to Salt Lake City by mid-November 1889, to Provo on March 7, 1890, and the rest of the way to Grand Junction on June 10. The line was completely relocated out of the canyon of the Price River from Grassy Trail to Woodside, and into the Ruby Canyon of the Grand (Colorado) River from Whitehouse to Crevasse, Colorado. Beyond Crevasse, the RGW leased the D&RG track to Grand Junction in December 1889 and subsequently widened its gauge. The Rio Grande Junction Railway, owned jointly by the D&RG and Midland, was completed to Grand Junction on November 15, 1890, and through service began the next day over the RGW and both eastern roads, the D&RG having completed its standard gauge line over Tennessee Pass. All branches were also converted, except for short narrow-gauge sections at the ends of the lines into Bingham and Little Cottonwood Canyons.
For the next ten years, the RGW operated as an independent standard gauge bridge line connecting Grand Junction to Salt Lake City and Ogden, with branches to sources of valuable minerals. Through its new subsidiary, the Utah Central Railroad, the RGW acquired several Salt Lake City-area lines in 1898, finally adding to its system the branch to Park City through Parley's Canyon that had been chartered in 1881. The RGW teamed up with the Colorado and Southern Railway, which had recently been split from the bankrupt Union Pacific Railroad, and stretched north-south from Wyoming through eastern Colorado into Texas, to jointly buy control of the connecting Colorado Midland Railway. RGW stock prices rose, delaying a takeover by the D&RG until George Gould arrived. Gould, owner of the Missouri Pacific Railroad (MP), wished to create a transcontinental railroad system, and identified the D&RG/RGW as the best route west into Utah. The MP began buying D&RG stock in 1900, and the D&RG did the same with the RGW. Palmer still owned a controlling interest in the RGW, but he came to an agreement to sell the company to Gould, and Gould management, including new president Edward T. Jeffery, took over on July 1, 1901.
Improvement of the standard-gauge main line through Utah to relieve congestion had begun in 1898, when the RGW added a second track to the steep 4% grade to Tucker on the west side of Soldier Summit. The shallower east-side grade was similarly doubled to Colton in 1906, and further to Kyune and from Castle Gate to Helper in 1909. Construction began on a new low-grade line west of the summit in 1912, when the D&RG added a track between Detour (the west end of the realignment) and Thistle. The new line, with a double hairpin curve, was completed the next year, as was a second track between Kyune and Castle Gate, completing a double-track line between Thistle and Helper, with a maximum grade of 2.4% on the east slope and 2.0% on the west. Local competition arrived in 1912, when the United States Smelting, Refining and Mining Company, which owned coal mines southwest of Price, organized the Utah Railway (originally the Utah Coal Railway). U.S. Smelting objected to the D&RG's charging of higher freight rates due to the mines' location on a branch line, and began to build its own line over Soldier Summit into the Utah Valley. The two companies reached an agreement in November 1913, where the D&RG would operate the Utah Railway between a junction near Castle Gate and the mines, and the unfinished line between Thistle and Provo would be completed as a second track. This arrangement began with the completion of the road in 1914, and the D&RG now had a double-track line between Provo and Helper. Three years later, the Utah Railway began independent operations between the mines and Provo under a reciprocal trackage rights arrangement that has persisted to the present, where each company allows the other to use its half of the double-track line.
The WP was completed in 1910, but its construction had given the D&RG enormous debts. After periods of ownership by Eastern bankers, the courts appointed two local trustees in 1935. The system was slowly rebuilt into a profitable enterprise, and in 1947 it was reorganized as the Denver and Rio Grande Western Railroad. After buying the Southern Pacific Transportation Company in 1988 and adopting the latter's name, the D&RGW became part of the Union Pacific Railroad in 1996.
With the level of the Great Salt Lake rising in the mid-1980s, the D&RGW and UP came to a trackage rights agreement, where the D&RGW would use the UP's higher line between Salt Lake City and Ogden, and in exchange the UP could use the D&RGW between Salt Lake City and Provo, a better-designed route than the UP's. The majority of the ex-D&RGW north of Salt Lake City is now the Denver and Rio Grande Western Rail Trail, while the UP has sold its Sharp Subdivision north of Provo to the Utah Transit Authority, which operates the Sandy/Salt Lake light rail line and contracts with the Salt Lake City Southern Railroad for freight.
|Mesa||Grand Junction||450.0||Grand Junction||Junction of Tennessee Pass Line/Moffat Line (1890-present) and Gunnison Line (1882-present)|
|468.9||Mack||Junction of Uintah Railway (1904-1939)|
|528.1||Thompson||Junction with Ballard and Thompson Railroad (1912-1950)|
|533.8||Brendel||Junction with Cane Creek Branch (1962-present)|
|Emery||Green River||555.2||Green River|
|602.9||Mounds||Junction with Sunnyside Branch (1899-present)|
|Spring Glen||Junction with Kenilworth and Helper Railway (1907-1926)|
|Helper||626.4||Helper||Junction with Kenilworth Branch (1926-1960s) and Spring Canyon Branch (1912-1970s)|
|628.8||Utah Railway Junction||Junction with Utah Railway (1914-present)|
|Utah||638.9||Kyune||Junction with Jennings and Potter's Quarry Branch (1892-1917)|
|644.8||Colton||Junction with Pleasant Valley Branch (1882-present)|
|Tucker||Original junction with Pleasant Valley Branch (1882)|
|681.0||Thistle||Junction with Marysvale Branch (1890-1983)|
|Springville||695.8||Springville||Junction with Tintic Branch (1891-present)|
|Provo||701.1||Provo||Junction with Orem Branch (1946-1970s) and Provo Canyon Branch (1899-1970)|
|American Fork||715.0||American Fork|
|Midvale||734.9||Midvale||Junction with Bingham Branch (1882-present) and Little Cottonwood Branch (1882-1964)|
|South Salt Lake||742.0||Roper||Junction with Park City Branch (1900-2005)|
|Salt Lake City||745.1||Salt Lake City|
|Davis||North Salt Lake||750.3||North Salt Lake|
|West Bountiful||753.9||Woods Cross|
|Farmington||Farmington||Junction with Lake Park Branch (1887-1925)|
|Weber||Roy||Roy||Junction with Hooper Branch (1905-1959)|