The Niles Canyon Transcontinental Railroad Historic District (NCTR) is an 11.6 mile-long segment of the first Transcontinental Railroad as it passes through Niles Canyon (Alameda Cañon), Sunol Valley, and Arroyo de la Laguna between the San Francisco Bay area and the Amador Valley. This rail line and its right-of-way winds from the Niles district of Fremont to Pleasanton via Sunol. The NCTR contains many features and characteristics of early western railroading that have been otherwise lost. Additionally, the NCTR has a rural setting largely unchanged from the time of the line’s original construction in 1865-69. Located in the San Francisco metropolitan area with over seven million people the NCTR retains much of the historic integrity and character from the time of its construction. The construction of the roadbed is now particularly unique in the western United States. Stemming from the 1853 survey and 1865 design, the narrow roadbed and sharp turns were characteristic of the formative period of railway construction. Most similar roadbeds were obliterated as railroad practice modernized beginning in the 1890’s. The ruggedness of the canyon precluded efforts to improve the roadbed. Except for the bridge replacements (1896-1906) the roadbed remained essentially unaltered. This was because the line was relegated to secondary service only about ten years after it was built. As a result many of the landsacpes through the canyon remain pristine. Principal contributing resources include stone works from the original 1865 construction, the 1884 Sunol Depot and three major steel bridges including a rare pin connected Pratt Truss. The right of way also contains the remains of the transcontinental telegraph line of 1869.