May 10th has a lot of memorable events linked to it, such as the first official Mother's Day celebration.
But an event that helped forge the growth of this country happened at Promontory Summit, Utah when the Golden Spike was hammered in to join the two railroads and thus, unite the country. After a seven-year race, the Central Pacific and the Union Pacific railways joined at Promontory Point, Utah. Coast-to-coast travel time was reduced, in that instant, from four to six months to six days.
Actually, there were four spikes. You can read about them here: http://www.nps.gov/gosp/historyculture/upload/Spikes.pdf
This revolutionary new technology, the railroad, was built largely at the hand of immigrants. The freed slaves and former Uion and Confederater soldiers also played key roles in the construction of the railroad that unified the Nation. The amazing accomplishment of these hard working, underpaided, uneducated men has seldom been equaled.