With the end of the Civil War, competing railroads from Missouri took advantage of their initial strategic advantage for a construction boom. The Hannibal and St. Joseph Railroad (H & SJ) completed the Hannibal Bridge which was the first bridge to cross the Missouri River in July 1869 in Kansas City. This in turn connected the Kansas Pacific trains that went from Kansas City to Denver, which had built the Denver Pacific, and connected to the Union Pacific. In August of 1870 the Kansas Pacific put the last nail that connected with the line Denver Pacific in Strasburg (Colorado) and the first authentic Atlantic-Pacific railroad of the United States was complete.
On June 4, 1876, a fast train called Transcontinental Express arrived in San Francisco via "first transcontinental railroad" only 83 hours and 39 minutes after its departure from New York City. Only ten years earlier the same trip would have taken months by land or weeks by boat.