It was 146 years ago today, May 10, 1869, that the ceremonial spike (actually more than one) was driven into the meeting point of the Union Pacific Railroad and the Central Pacific Railroad. That’s when it became the transcontinental railroad, and traveling across the country no longer meant months in a wagon or on a ship sailing around South America. The transcontinental railroad was a great idea, but making it into a competition had some unintended consequences.
Congress made the fool's mistake of assuming some motivating rationality on the part of the railroad companies, and not just base greed, so they didn't dictate just how, when, or where the rails must meet. When Central and Union crews ran into each other in northern Utah, instead of merging the lines right away, they set off building miles of parallel grading, with each company hoping to acquire more mileage and thus more of the reward money. With a kind of paternal exasperation, then, Congress had to set a junction point; and they chose Promontory, Utah—a little tent town of railroad workers and prostitutes just north of the Great Salt Lake.
The ceremonial joining of the railroads didn't go as smoothly as you might have heard. It was a publicity stunt, and it also meant the end of a job for those who built the railroad. Read about what really happened on that day at mental_floss.