On April 7, 1933, Prohibition in the United States was repealed for beer of no more than 3.2 percent alcohol by weight — eight months before the ratification of the XXI amendment, which repealed the 18th (or Prohibition) Amendment.
The enabling legislation was the Cullen – Harrison Act, which figured the low alcohol content as the excuse to get around the 18th Amendment’s prohibition of intoxicating beverages. The act passed Congress on March 21, 1933, and was signed into law by Franklin Delano Roosevelt the next day.