With these in hand, the railroads began work in 1866 from Omaha and Sacramento, forging a northern route across the country. In their eagerness for land, the two lines built right past each other, and the final meeting place had to be renegotiated.

The first American transcontinental railroad, completed in 1869, was a dual-effort construction project that began from two distinct geographical locations. The Union Pacific Railroad began its westward journey from Council Bluffs, Iowa, and Omaha, Nebraska, moving across the Great Plains and through the Rocky Mountains. Simultaneously, the Central Pacific Railroad started its eastward construction in Sacramento, California, carving through the formidable Sierra Nevada mountains. These two lines eventually met at Promontory Summit, Utah, where the ceremonial "Golden Spike" was driven on May 10, 1869. This historic connection revolutionized travel in the United States, reducing a cross-country journey that previously took six months by wagon or ship to just a few days by rail. While later extensions connected the line to the Pacific coast at Oakland and San Francisco, the inland termini of Omaha and Sacramento remain the historically recognized "start" points of this monumental engineering feat.