USA HISTORY

Detailed explanation-1: -As Central Pacific laid tracks eastward, Union Pacific was working westward and the race to Promontory Summit, Utah, where they would eventually meet on May 10, 1869, was on.

Detailed explanation-2: -From May-December 1869, Promontory was the terminus of the transcontinental railroad (the junction point for Central Pacific and Union Pacific Railroads).

Detailed explanation-3: -A central route following the Platte River in Nebraska through to the South Pass in Wyoming, following most of the Oregon Trail. Snow on this route remained a concern. A southern route across Texas, New Mexico Territory, the Sonora desert, connecting to Los Angeles, California.

Detailed explanation-4: -On May 10, 1869, the presidents of the Union Pacific and Central Pacific railroads meet in Promontory, Utah, and drive a ceremonial last spike into a rail line that connects their railroads. This made transcontinental railroad travel possible for the first time in U.S. history.