Who Built The Union Pacific Railroad. The point of conjoinment for the two railroads was established as promontory point, utah. Much of it was built by the central pacific railroad, building east from sacramento, california, and the union pacific railroad building west from omaha,.

The union pacific relied mainly on irish workers, many of whom were famine immigrants and fresh off the battlefields of the war. Much of it was built by the central pacific railroad, building east from sacramento, california, and the union pacific railroad building west from omaha,. The locomotives were 132 feet long and weighed 1.2 million pounds.