Work on the first transcontinental railroad began after President Abraham Lincoln approved the Pacific Railway Act of 1862, a landmark law that authorized the federal government to financially back the construction of a transcontinental railroad.
http://ocp.hul.harvard.edu/immigration/railroads.html
Gee, I wonder where the railroad companies were headquartered that received this bonanza. Could it be Lincoln's old friends and former employers?
Union Pacific was HQd in Omaha NB. Central Pacific was HQd in San Francisco. Since both were formed in 1862, Lincoln probably never worked for them.