A cold can of beer on a hot summer day is as American as it gets. But now that experience will cost you more, one of many unfortunate effects of the 10% tariff President Trump imposed on aluminum imports in March.

I say this as a fourth-generation brewer. My great-grandfather founded the Coors family business almost 150 years ago in Golden, Colo. In 1958 my uncle Bill Coors, now 101, led a team that created the first aluminum beer can. He couldn’t have imagined that his innovation would be caught in the crossfire of a trade...