As President Trump imposes tariffs on products from countries around the world, foreign governments are answering back with tariffs of their own.

China has targeted corn farmers and carmakers. Canada has put tariffs on poultry plants and air-conditioning manufacturers, while Europe will hit American steel mills and slaughter houses.

The retaliatory tariffs are an attempt to put pressure on the president to relent. And they have been carefully designed to hit Mr. Trump where it hurts: Nearly 8 million Americans work in industries targeted by the levies and the majority are Trump voters, a New York Times analysis shows.

The figures underscore the dramatic impact that a trade war could have on American workers, potentially causing Mr. Trump’s economic strategy to backfire. Mr. Trump has argued that tariffs will help boost American jobs. But economists say that retaliatory tariffs can cancel out that effect.