America's greatness being built on free trade is more or less an opinion, however a lot of amazing developments did come from having relatively free markets. Golden age may be strong language too, but the mild west did have very libertarian ideas. The east coast however government was expanding. But the innovations didn't seem to really happen till the 1900's. A lot of groundwork however was established prior to this.
1. The gold rush (a large amount of new monies)
2. Oil rigs had been installed and are producing, pipelines started.
3. Settlements had settled (namely they killed most natives, bears, birds, and buffalo)
4. And fiat currency centrally established (massive credit expansion)
5. Railroads had connected East and West, and almost equally important communications technologies... ie phone, morse code
These points to me led to lots of innovation. But also to lots of speculation. Namely in the 20's.
I personally don't think the US was completely built on free trade. But compared to today it may seem to be free trade, the government was roughly 1/10th it's present size. "free banking" existed (though it was still fractional-reserve). There was very little regulation or taxation (compared to now). There are better examples in history though, China in the 15th and 16th centuries, under the Ming Dynasty.
This dynasty was influenced by Taoism. The government did not issue banknotes, which were entirely privately issued; the tax rate was reduced from about 7.5% to 3.3%, and there were no regulations or tariffs (only one tax on imports that yielded about 40,000 taels a year on a trade of millions), unlike European mercantilism. Many people, especially the educated, were exempt from taxation whatsoever. Unfortunately, this ended with the conquest of China by the Manchus.
Going back to America however:
Point 3. Was subsidized. Gov't army did much massacring, and bullets were handed out freely to citizens in order to kill undesired things.
point 4. Obviously gov't involvement
point 5. Gov't subsidized