[4] After several years of financially draining battle, the two companies came to an agreement in 1880, and the D&RG, under the direction of William J. Palmer, set its sights on Salt Lake City.

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 old grade has been flooded until it leaves the lake to the north, rising to an elevation of 7,967 feet (2,428 m) above sea level before descending, via a pair of switchbacks, to Starvation Creek.

[10] The lines of this company and the Sevier Valley were included in the far-reaching charter for the Denver & Rio Grande Western Railway, incorporated on July 21, 1881[6] 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,[11] and Palmer confirmed this in September.

[7] 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.

[13] D&RG and D&RGW crews met at a point now known as Desert, 14 miles (23 km) west of Green River, on March 30, 1883, and trains began running between Denver and Salt Lake City several days later.

[16] With the line into Utah complete, the D&RG system consisted of a narrow gauge main line from Denver to Ogden, passing through or over Colorado Springs, Pueblo, the Royal Gorge, Salida, Marshall Pass, Gunnison, the Black Canyon of the Gunnison, Montrose, Grand Junction, Green River, and Salt Lake City.

Continuing on, the line passed through the Price Canyon, including the Castle Gate rock formation, as it rose to the top of the Wasatch Range at Soldier Summit.

The final stretch generally followed the Great Salt Lake's shore to Ogden, where it connected to the Central Pacific Railroad.

To raise the money to convert the line, which would require about 100 miles (160 km) of new railroad where the existing grade was too steep or curvy, he incorporated a new Rio Grande Western Railway.

[21]) The State Line and Denver Railway was incorporated May 16, 1889[6] with the power to build east to Glenwood Springs, Colorado, then the terminus of the Midland.

[22] Construction began immediately, the line being converted from Ogden to Salt Lake City by mid-November 1889,[23] to Provo on March 7, 1890,[24] and the rest of the way to Grand Junction on June 10.

[27] 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.

[29] 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 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.

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.

[35] The majority of the ex-D&RGW north of Salt Lake City is now the Denver & Rio Grande Western Rail Trail, while the UP has sold its Sharp Subdivision north of Provo to the Utah Transit Authority, which operates the TRAX Blue Line (light rail) along the corridor, as well as contracts with the Salt Lake City Southern Railroad for freight.

[38] The Rio Grande obtained control of the narrow gauge Wasatch & Jordan Valley Railway in 1881 which had been built up Little Cottonwood Canyon.