The United States has imposed special protection on imports from China for decades, but the long, historical view shows the enormous scope of tariffs imposed in 2018. At the end of 2017, 8 percent of US imports from China were subject to some form of special trade protection. At the end of 2018, that number surged to over 50 percent, a one-year rise of over 42 percentage points. The next largest increase was 8 percentage points in 1986, when US special protection peaked at covering 39 percent of US imports from China.
This chart was adapted from Chad P. Bown and Eva Zhang’s blog, “Will a US-China Trade Deal Remove or Just Restructure the Massive 2018 Tariffs?”