The Pacific Railroad Acts of 1862 were a series of acts of Congress that promoted the construction of a "transcontinental railroad" in the United States through authorizing the issuance of government bonds and the grants of land to railroad companies. In 1853, the War Department under then Secretary of War Jefferson Davis was authorized by the Congress to conduct surveys of five different potential transcontinental routes from the Mississippi ranging from north to south. It submitted a massive twelve volume report to Congress with the results in early 1855. However, no route or bill could be agreed upon and passed authorizing the Government's financial support and land grants until the secession of the southern states in 1861 removed their opposition to a central route. The Pacific Railroad Act of 1862 was the original act. Some of its provisions were subsequently modified, expanded, or repealed by four additional amending Acts: The Pacific Railroad Act of 1863, Pacific Railroad Act of 1864, Pacific Railroad Act of 1865, and Pacific Railroad Act of 1866.

A transcontinental railroad or transcontinental railway is contiguous railroad trackage, that crosses a continental land mass and has terminals at different oceans or continental borders. Such networks can be via the tracks of either a single railroad or over those owned or controlled by multiple railway companies along a continuous route. Although Europe is crisscrossed by railways, the railroads within Europe are usually not considered transcontinental, with the possible exception of the historic Orient Express. Transcontinental railroads helped open up interior regions of continents not previously colonized to exploration and settlement that would not otherwise have been feasible. In many cases they also formed the backbones of cross-country passenger and freight transportation networks. Many of them continue to have an important role in freight transportation and some like the Trans-Siberian Railway even have passenger trains going from one end to the other.