It interesting to note the that last time Trump imposed tariffs on China, the retalitatory tariffs cost US farmers billions of dollars. The deficit soared because Trump had to cover the farmer's losses.

While there were some need for tariffs in the 18th century to protect USA  industry, the need for tariffs decreased with the use of income tax and freer trade.

However, tariffs were broadly used in the 1930s which deeped the depression. 

Trump has stated that tariffs wouldn't increase prices, but this was said during his election campaign which was filled with lies.  Because the economies of Canada and Mexico are so integrated with the USA, both countries would be hit hard by tariffs. Do you remember NAFTA? 

Most economists regard tariffs as dangerous and inflationary. 

Trump has threatened a trade war with the BRIC which would start with a 100% tariff on everything. 

I have had much to say about Trump, tariffs and mass deportations on my twitter page. None of his actions make good economic sense.