Promontory in Box Elder County, Utah, United States is an area of high ground west of Brigham City, Utah and northwest of Salt Lake City. Standing at an elevation of above sea level, it lies to the north of the Promontory Mountains and the Great Salt Lake. It is notable as the location of Promontory Summit where the First Transcontinental Railroad in the United States was officially completed on May 10, 1869.
By the summer of 1868, Central Pacific had completed the first rail route through the Sierra Nevada and was now moving down towards the Interior Plains and the line of the Union Pacific. More than 4,000 workers, of whom two thirds were Chinese, had laid more than of track at altitudes above . In May 1869, the railheads of the Union Pacific and the Central Pacific railroads finally met at Promontory Summit, Utah Territory. A specially-chosen Chinese and Irish crew had taken only 12 hours to lay the final of track in time for the ceremony.