Some dominant companies of course emerged in that era, but I'd be interested to see evidence that companies that weren't insulated from competition by government policies actually used their dominance to harm consumers.
Also, the fact that some companies became very dominant doesn't mean ipso facto that they harmed consumers. If a company becomes huge fair and square (as opposed to via regulatory capture or other coercive means), it may just mean that people like their product the best.
Those didn't exist in the 1800s. The rise of the corporation occurred after the 1830s, when Congress no longer had to approve of every single company's existence.
After that, it was Laissez-faire economics for over 50 years. https://en.wikipedia.org/wiki/Laissez-faire ... basically ending with the Sherman Anti-Trust Act when Americans realized that was a bad idea.
http://ncpedia.org/united-states-v-american-tobacco-co
> protected by tariffs
Globalization wasn't a big thing in the 1800s. US Companies basically only had to worry about other US Companies. There was some foreign trade, but not much.
Within the US, a major entity like the Tobacco Trust had the power to set prices. When you're the only company in the entire US, you have the ability to stomp out competition like that.