This car is named for Promontory Summit, Utah, just north of Great Salt Lake and the site selected for the joining of the Union Pacific and Central Pacific Railroads. Completion of the railroad–the greatest engineering feat of the 19th century–culminated in a celebration there on May 10, 1869. Promontory Point, often erroneously referred to as the location for the ceremony, juts out into the lake itself. It was the location of a saltworks for many years.