Contrary to popular religious belief, we already levy huge tariffs on imports from unpopular countries like China - unless, perhaps, a certain firm is big enough to buy a few pages of exemptions for themselves in the next "Free" Trade Agreement - so the only thing left to accomplish with a general import tariff on everything is to beat up those scammers in Denmark and New Zealand who are flooding us with cheap cheese and wine. :)
A Free Trade myth easily debunked.
For FY 2010 the USA collected $25 Billion in tariff revenues. That sounds like a lot but when you consider the USA imports $2.5Trillion every year that works out to around 1%. LOL.
Ref. Tariffs in the United States.