From Wikipedia:

Many manufacturers use the Made in the U.S.A. label as a selling point with varying degrees of success. This is largely because, in the wake of lowering or eliminating import tariffs, the proportionate quantity of manufactured goods made within the United States has steadily declined, especially within the last three to four decades. American companies have largely focused their manufacturing operations in poorer nations, largely China, where labor is cheaper and labor and environmental laws are comparatively insignificant.

Many Americans view this trend with disdain for a variety of reasons. Some worry that their nation has lost both industrial capacity and essential manufacturing jobs, some may be concerned with the exploitation of non-American workers in sweatshops while others believe that this has drastically decreased the general availability of high quality products. Therefore a product bearing a Made in the U.S.A. label can appeal to an American who seeks high quality products produced domestically under American labor and environmental laws.