Answer:
The Transcontinental Railroad in the United States is the name of a railroad line across the United States that linked the city of Omaha (Nebraska) with Sacramento (California) in the 1860s. This railroad line linked the rail network of the east and west and its construction required enormous feats of engineering and work to cross plains and high mountains. It was an achievement of the presidency of Abraham Lincoln, which was completed four years after his death. The two railway companies that built the line were the Union Pacific and Central Pacific.
This infrastructure work created a transport network that revolutionized the population and economy of the Western United States. With this railroad the caravans of wagon trains of the Old West were not necessary and became obsolete. This greatly increased the population of white settlers in the West, while the native population decreased considerably in the regions where the railway crossed.
The railroad route followed the main roads used for the opening of the West, the so-called Oregon Route, the Mormon Route, the California Route, and the Pony Express. The Central Pacific company built 1,110 kilometers of railroad, starting in Sacramento, California, and continuing east. The Union Pacific Company built 1,749 km of track, starting at Council Bluffs, and continuing west. Most of the stretch of the Union Pacific was built by Irish workers, and by veterans of the Union and Confederate armies. The stretch of the Central Pacific was built primarily by Chinese immigrants.
There were rivalries between the two companies and it is known that each lone sabotaged the work of the other. These attitudes and actions were promoted in large part by the way in which the government gave the money to the companies. When they arrived near the junction point, they changed the routes so that each company could claim government grants on the same plot of land. To end the fighting, Congress finally declared where and when the railroads should meet.