One only needs to take an Amtrak train bound from Baltimore to Philadelphia to witness scores of abandoned factories — all victims to one-sided U.S. free-trade pacts with cheap labor countries like China.

While there is a valid argument that America’s industrial base was overtaken by technological advances, such as automation and robotics, the fact that even modern American manufacturing plants have joined the ranks of the abandoned show how nations like China, Mexico and India are capturing America’s techno-industrial base.

Companies like Apple, Carrier, Leviton, Whirlpool, La-Z-Boy and Harley-Davidson were eager to outsource their manufacturing to foreign locations, where cheap labor abounds.

Trump’s tariffs leave these and other countries with a simple choice: Either maintain or return manufacturing of their products back to America or face a punitive import tax on goods imported from their factories abroad.

President Donald Trump’s imposition of “fair trade” tariffs has worked the way it was intended to — boosting the number of U.S. manufacturing jobs. Sectors that have benefitted from Trump’s protectionist policies include solar panels, washing machines, flat screen television, steel and aluminum manufacturing.

So far, manufacturing jobs are increasing across the nation, especially in distressed cities like Buffalo, N.Y.; Louisville, Ky.; and Huntsville, Ala., where U.S. firms abandoned their plants for the allure of cheap overseas labor but now are “reshoring” jobs lost to foreign outsourcing.

Tariff protections for U.S. steel and aluminum have not only resulted in an improved outlook for investors in both industries but have translated into more jobs and greater manufacturing capacity in the United States.

Trump, like unsuccessful 2016 Democratic presidential candidate Bernie Sanders, promised to act against countries like China, which had enjoyed an unbalanced trade relationship with the United States that emaciated America’s blue-collar labor force and the local economies that were left shattered by job loss. Since Trump retaliated against America’s manufacturing competitors in Asia and Latin America, U.S. companies are thinking twice about off-shoring manufacturing.

Some are opting to assemble products at U.S. factories, using a combination of domestically-made components and those manufactured abroad. For this “one foot in America, one foot abroad” policy, companies are seeking tariff relief for components that require cost-prohibitive assembly line installation. These partial U.S. manufacturing firms, while not perfect, are a step in the right direction. Some manufacturers of automotive parts have even moved back to Michigan from China.

Overall, Trump’s tariffs are having the desired effect in key industries.

One is medical technology, an area in which the United States always excelled. For instance, Insulet Corporation, the manufacturer of insulin delivery systems, is moving its plant from China to Massachusetts. Other bio-industry and pharmaceutical firms are relocating manufacturing from China and Europe to states like New Jersey and Rhode Island.

Level-headed trade policies by Trump have helped return some semiconductor manufacturing jobs from China, Malaysia and Taiwan to American shores.

While Trump’s tariffs have come under fire from some traditional economists, in the long-run America will be better off for adopting a sane trade policy. And polls show that many voters are prepared to endorse that strategy in the midterm elections.

Whitt Flora is a former Washington correspondent for the Columbus Dispatch and writer for Aviation Week and Space Technology.