But many economists argue that the protective benefits of tariffs have been outweighed by negative effects. For example, tariffs make any products that manufacturers buy from abroad more expensive, increasing costs for American businesses and potentially making American products less competitive when sold overseas.

Tariffs have offered American companies some protection from Chinese imports, allowing them to gain a greater share of business in the United States, according to a study released Dec. 23 by two economists at the Fed, Aaron Flaaen and Justin Pierce. But those positive effects of tariffs are more than offset by the negative effects of the trade war, including the higher prices companies must pay to import components from China, and the retaliatory tariffs China placed on the United States in response, the economists said.

The researchers also found that the American manufacturing industries that were most exposed to tariff increases had shed more jobs than industries that were less exposed, though they do not find that the tariffs had a strong effect on industrial production.

Some might argue that the negative effects of tariffs are warranted if they protect the manufacturing sector, but the findings suggest the tariffs increased producer prices without raising manufacturing employment or output.

“While the longer-term effects of the tariffs may differ from those that we estimate here, the results indicate that the tariffs, thus far, have not led to increased activity in the U.S. manufacturing sector,” the economists said.

So far, tariffs imposed to protect the American metal and washing machine industries have had a mixed effect. In the steel industry, for instance, the protection against imports helped prompt United States producers to invest billions of dollars in new facilities that they hope will be more efficient.

But the price of steel plunged, in part as a result of lower demand from manufacturers, putting pressure on the steel makers. In December, United States Steel said it was going to indefinitely idle most of a mill near Detroit. Some 1,500 workers from the facility got layoff notices. U.S. Steel also cut its capital spending forecast for this year, to $875 million from $950 million.