Generally, you're allowed to make up to 100 gallons of beer per person – with a cap of 200 gallons per household, regardless of the number of adults living there.
In 1919 the prohibition act was passed, and brewing alcohol became illegal. However, the 21st amendment in 1933 saw the laws being repealed. In 1979 President Jimmy Carter abolished the age-old laws of prohibition and made it entirely legal to brew beer and wine at home, at a federal level.