A map show is rail lines that developed in the US as a result of westward expansion what lines made up the first transcontinental railroad?

The first transcontinental railroad in the United States was completed in 1869 and was primarily composed of two major rail lines: the Central Pacific Railroad, which started in Sacramento, California, and the Union Pacific Railroad, which began in Omaha, Nebraska. These two lines met at Promontory Summit in Utah, marking a significant milestone in transportation and facilitating westward expansion. The construction of this railroad drastically reduced travel time across the continent and contributed to economic growth and settlement in the West.