Donald Trump and the long history of ‘sticky’ US tariffs

In a matter of weeks, President Donald Trump’s tariff blitz has erased a century of US trade liberalisation. Economists say it could take a lot longer to build back.

Past periods of protectionism show that once trade barriers have been erected, they can prove very difficult to dismantle. “What can go up quickly does not necessarily come down fast,” said Doug Irwin, a professor at Dartmouth College who has written widely on trade.

The sweeping tariff increases of the 1930 Smoot-Hawley…