Why did Abraham Lincoln support the Pacific Railroad Act?

He was one of the main investors in the railroads.

He believed a transcontinental railroad was needed to connect the far-flung parts of the Union.

He knew if the Union didn't build the railroad, the Confederacy would.

the construction

Explanation:

In Lincoln's mind, the railroad was part of the Civil War effort. The new line would support communities and military outposts on the frontier ... A transcontinental railroad, Lincoln hoped, would bring the entire nation closer together - would make Americans across the continent feel like one people.