Postcard of Golden Gate photographed by Asahel Curtis, 1928. Golden Gate Canyon is in the northwestern region of Yellowstone NP. The northern portion of the Grand Loop Road traverses the canyon, connecting Mammoth Hot Springs with park features to the south. A road was first built through the Golden Gate in 1884-85, replacing a steep, difficult road over Snow Pass. The work included a wooden trestle where a cliff face precluded grading. In 1900 the viaduct was rebuilt as a concrete structure under the supervision of Captain Hiram M. Chittenden. The viaduct was replaced in turn in 1930-34, the outcome of a program to widen the road. The widened viaduct was itself replaced in 1977. Yellowstone National Park is a national park located primarily in the state of Wyoming, although it also extends into Montana and Idaho.