From From the River to the Sea: The Untold Story of the Railroad War That Made the West, by John Sedgwick (Avid Reader / Simon & Schuster, 2021), Kindle pp. 35-37, 47:
The first train to venture into the uncharted West was the Union Pacific, a new railroad company that had been created by Congress solely for the purpose. Extending out from the Midwest, the UP had linked up with another federal creation, the Central Pacific, coming in from California. Together, they created that first transcontinental, the Pacific Railway. May 10, 1869, was a glorious day for the young country, as it marked the occasion when the two lines met at Promontory Point in the Mormon country north of Salt Lake City. It was a fantastic engineering achievement and a triumph of heroic perseverance, especially by the track layers, mostly Irish going west, mostly Chinese coming east, who engaged in a spirited competition to outdo the other. (That honor fell to the Chinese.) But when judged purely on commercial terms, the line was a dismal failure. It was the moonshot of the railroad era, an accomplishment that was only symbolically significant. It was all too telling that when Leland Stanford, one of the four powerful money men behind the Central Pacific, tried to slam home the Golden Spike with a monstrous hammer, he missed it entirely. This was especially embarrassing since the blow was to complete an electric circuit that would automatically send the thrilling news out over the telegraph wires that accompanied the tracks. A telegraph operator had to key in the word that flew around the world—“DONE!”—setting off a chorus of bell-ringing all across the country, led by Philadelphia’s cracked Liberty Bell. In San Francisco two hundred and twenty cannons boomed forth; Washington, D.C., fired a hundred more. Chicago greeted the news with the biggest parade of the century. And so it went, total jubilation all around the country. It was as if these intrepid Americans had discovered a new continent, come up with a spectacular invention, or won a world war. And, indeed, they had done all of these. What they had not done was find a sound business rationale for the endeavor.
A railroad to the Pacific had first been proposed by a New York merchant, Asa Whitney, back in 1844, and was long championed by the visionary engineer Theodore Judah. But it was the former railroad lawyer Abraham Lincoln who pushed the initiative through as president in the war year of 1862. Lincoln had also set the width of track for the railroad, establishing the peculiar distance of four feet eight and a half inches as the national standard for a train system.
[Endnote:] Previously, American trains ran on a maddening hodgepodge of track widths. When Lincoln went by train from Springfield, Illinois, to New York City to receive the Republican presidential nomination for president in 1860, his trip took four days because of all the delays in transferring to trains on five different widths of track. If he had ridden a single width of track, the trip would likely have taken one.