A fast and easy way to transport goods between the east and west coasts of the US, as well as opening the west for settlement, was important for the expansion of the country. Lincoln signed the Pacific Railroad Act into law on July 1, 1862 which established the two main lines—the Central Pacific would build from the west, starting in Sacramento, CA and the Union Pacific from the mid-west, starting in Council Bluffs, IA. Each company was issued government bonds for every mile of track and also land grants along the right of way so there was a lot of incentive to build as much track as quickly as possible.
It was a long and hard chore to build over and through mountains, across rivers and chasms, but after six years the two companies were near the meeting point. Advance crews who prepared the rail beds met at Promontory Summit, passed each other and kept building. Two separate cuts in the hillside north of the summit are still visible today. Finally on April 10, 1869, Congress passed a joint resolution setting the joining of the two rail lines at Promontory Summit. On May 10, 1869 a large crowd of dignitaries, railroad workers and reporters gathered to witness the driving of the final spike. A ceremonial golden spike was tapped into a pre-drilled hole by the head of each rail line. The spike is now at Cantor Arts Museum at Stanford University.
The visitor center has a small museum and a film. Interpretive signs are along a walkway outside that leads to the meeting of the tracks. During the summer the trains (not the actual locomotives but very precise reconstructions) are run out of the engine house Wednesday through Sunday with re-enactments of the Driving of the Last Spike Site ceremony on Saturdays. We were a day early for the season but we did get to see the trains in the engine house.
The museum and film are accessible. The engine house parking lot has an accessible space. The walkway is paved to the meeting site then becomes gravel so not all of the signs can be easily reached. The Big Fill Loop Trail is not accessible.
The visitor center parking lot has long RV spaces. RVs will fit in the engine house lot but are not permitted on the east and west auto tours which follow the original railroad grades.