The development of rich precious-metal mines in northern Piute County in the late 1880s encouraged expansion of the Rio Grande Western Railway lines. In 1890, while the narrow gauge Rio Grande Western mainline between Ogden and Denver was being widened, a standard gauge roadbed was built south from Thistle to Ephraim but laid with three-foot-gauge track. During the two-year transition from narrow gauge to standard gauge, the Sevier Railway became the repository for most narrow gauge equipment remaining in the Utah half of the Rio Grande Western. Citizens of Sevier County formed the Sevier Railway in May 1891 and purchased the right-of-way to build tracks from Manti to Marysvale for use by Denver and Rio Grande Western trains. The rails did not reach the mining area of Belknap, five miles north of Marysvale, until 1896 after construction of the labor-intensive Eagle Rock Tunnel, and the track was finally completed to Marysvale in 1900. For three-quarters of a century, the Marysvale Branch carried traffic ranging from short peddler freights and long coal drags to mixed freight and passenger trains, first powered by steam and later by diesel engines. Road development and improved bus service after World War I reduced passenger traffic along the line, and by 1947 both passenger and freight revenues had fallen below operating expenditures, leading the Denver and Rio Grande Western to request an end to passenger service. In 1983, a mudslide at Thistle shut down the mainline and blocked southern access to the Marysvale Branch. Along this historic railroad grade are surviving features including the 200-foot Eagle Rock Tunnel, completed in 1896 and curved to accommodate the Sevier River; wooden box culverts typical of the late 1800s; concrete culverts with headwalls; and erosion-control structures built to protect the railroad where it closely followed the Sevier River.