Deseret News Share this story Annie Barker, Deseret News It was on this date 152 years ago today, that the world changed at Promontory Summit in Utah’s Box Elder County. On May 10, 1869, one of the greatest technological achievements of the 19th century — the completion of the first transcontinental railroad across the United States — occurred when the Union Pacific Railroad and the Central Pacific Railroad met as one to transform a nation reeling from the aftermath of the Civil War. That historic feat was commemorated during a celebration Monday at Golden Spike National Historic Park. The celebration included reenactments of the original 1869 ceremony, steam locomotive demonstrations, a recreation of the historic “champagne photo,” and special exhibits of historic objects found along the railroad.