The American wine industry faced a major setback in 1920 when the Eighteenth Amendment to the United States Constitution prohibited the manufacturing, sales, transportation, importation, exportation, delivery or possession of intoxicating liquors for beverage purposes. Commonly referred to as Prohibition, continued for thirteen years. Prohibition nearly destroyed what had become a thriving, national industry.
A few types of liquor were exempt. Medicinal wines were allowed for sale by pharmacists, if accompanied by a prescription by a doctor. Medicinal wine tonics, otherwise known as fortified wines, were allowed without a prescription. Sacramental wine was also a loophole of Prohibition.
The general public was also allowed to make up to two hundred gallons of fruit juice or cider annually. This could be made into a concentrate that was perfect for making wine. Grape concentrate from California was shipped to the East Coast, along with strong recommendations NOT to add sugar or yeast because fermentation would take place. Of course, this found its way into the hands of bootleggers who did just that, until the government stepped in and stopped the sale of grape juice, preventing illegal wine production.
Although Prohibition came to an end in 1933, the impact would be prevalent for decades. Wine was no longer drank for its taste, but for the effect. Americans had lost their interest in quality wine. In 1900, forty different American wineries had won medals at the Paris Exposition. In 1920, California had more than 700 wineries. When Prohibition ended, there were only 160 left. Thousands of acres of grapes were plowed under. Prohibition was devastating to the majority of American wine producers.