Since the General Agreement on Tariffs and Trade was adopted by the United States and other major trading nations in 1947, the average level of global tariffs levied against U.S. exports has dropped sharply from 22 percent to under 5 percent.  That trend has continued under the 1994 Uruguay Round Agreement, which established the WTO while beefing up the dispute settlement mechanism to keep barriers down.
The result has been a healthy increase in U.S. trade, including exports. Since the creation of the WTO, U.S. exports of goods and services have jumped from $700 billion in 1994 to $2.5 trillion in 2019. As a share of the domestic economy, exports have climbed from under 10 percent to 12 percent. The WTO has also encouraged lower U.S. barriers to trade, to the benefit of tens of millions of consumers here at home, as well as import-consuming U.S. producers.
Jesse Singal eloquently responds to the unhinged reaction to the recent letter in Harper’s calling for a return to liberal values  (although I don’t quite follow the “hit dog will holler” analogy).