Explain how the transcontinental railroad was built between 1863 and 1869, connecting Sacramento to the rest of the country, and identify the "Big Four."
Reaching California from the rest of the country was still slow and hard, even twenty years after the Gold Rush began -- exactly the problem the transcontinental railroad was built to solve. Starting in 1863, the Central Pacific Railroad built east from Sacramento while the Union Pacific Railroad built west from Omaha, Nebraska, racing across mountains, deserts, and plains toward each other. The Central Pacific was financed and led by four businessmen nicknamed the "Big Four": Leland Stanford, Collis Huntington, Mark Hopkins, and Charles Crocker.
The two railroads finally met at Promontory Summit, Utah, on May 10, 1869, where a ceremonial golden spike was driven into the final rail. What had taken overland travelers four to six months in 1849 could now be crossed by train in about a week. Building the Central Pacific's half of the line, especially through the steep granite of the Sierra Nevada, required extraordinary labor -- performed overwhelmingly by Chinese immigrant workers, whose specific story is this important enough to deserve its own full lesson next week.
Mastery looks like: They can name the two railroad companies, the Big Four, and the date and place the railroad was completed.
Common stumbles: Confusing which company built from which direction; underestimating how dramatically the railroad shortened travel time.