President Abraham Lincoln signed the Pacific Railroad Act, committing the federal government to support a railroad and telegraph line from the Missouri River to the Pacific via land grants and loan bonds, and chartering the Union Pacific (westward) and Central Pacific (eastward).
Central Pacific Railroad construction began with a ceremonial groundbreaking in Sacramento, California, marking the start of the west-to-east build toward the Sierra Nevada and beyond.
Construction began on the Union Pacific Railroad in Omaha, Nebraska Territory, establishing the eastern push of the transcontinental line across the Great Plains toward the Rocky Mountains.
Congress passed the second Pacific Railway Act, increasing land grants and improving financing terms to attract capital and accelerate construction after early funding shortfalls.
As Sierra Nevada construction intensified and labor was scarce, Central Pacific expanded recruitment of Chinese workers—who would become the majority of its workforce—reshaping the project’s labor system.
Roughly 2,000 Chinese workers struck for about a week in the Sierra Nevada, demanding better working conditions and pay. The strike ended without violence and highlighted worker organization on the project.
The Central Pacific completed the critical breakthrough of Summit Tunnel (Tunnel No. 6) at Donner Pass, overcoming one of the project’s hardest engineering barriers through the Sierra Nevada.
With track advanced to the Sierra summit, the Central Pacific opened a major mountain section, setting up the final push down into Nevada once the remaining gaps were closed.
Union Pacific track reached the new railroad town of Cheyenne, a key logistical base for pushing west over high-elevation passes and bridging difficult terrain in what is now southeastern Wyoming.
After completing the route up and over the Sierra Nevada, Central Pacific reached Reno, strengthening its supply line and enabling rapid track-laying across Nevada’s relatively flatter stretches.
In spring 1869, Congress and the two railroads agreed to meet at Promontory Summit, Utah Territory—an arrangement intended to end costly parallel track-building as both companies closed in on northern Utah.
Central Pacific crews laid about 10 miles of track in a single day, a highly publicized feat that capped an informal record-setting contest with Union Pacific and helped speed completion before the junction ceremony.
Central Pacific and Union Pacific tracks were joined at Promontory Summit, Utah Territory. A telegraphed “Done” signaled the completion of the first transcontinental railroad link between Omaha/Council Bluffs and Sacramento.
The New York Sun published an exposé of the Crédit Mobilier affair, revealing corrupt profiteering tied to Union Pacific construction contracts and setting off congressional investigations that damaged public trust in the project’s financing and governance.
Construction of the First Transcontinental Railroad (1862–1869)
