In the beginning, the USA had strong protectionist policies and unfettered business and trade within the USA between the states(inter state commerce) and territories. This was what built a great nation. The 16th amendment and reducing tariffs to nil is what did us in, all to make international corporations rich.
Wait a sec. you said we started with high import taxes and then they went down. What we're actually seeing is that we started with nothing and now we're rich. If that's "did us in" that we should "do us in" more often.