On Dec. 5, 1933, Americans liberated themselves from a legal nightmare called Prohibition by repealing the 18th Amendment to the Constitution. Today most people think Prohibition was fueled by puritanical Protestants who believed drinking alcohol was a sin. But the vocal minority who made Prohibition law believed they were marching in the footsteps of the abolitionists who sponsored a civil war to end another moral evil—slavery.

At least as important was the belief that Prohibition would produce health...