What factors led to the great expansion of u. s. industry in the late 1800s?

The country had just come out of it's worst war yet, and was becoming a player on the global stage. The USA started exporting and importing goods with other countries. So, to keep up with demand, we had to produce more, which led to factories and labor unions. Also, the Railway Act that President Lincoln signed helped spur the Industrial Revolution. Men like Rockefeller and Carnegie rose to power through the factories and helped build the rails.