Napa County wine is wine made in Napa County, California, USA. County names in the United States automatically qualify as legal appellations of origin for wine produced from grapes grown in that county and do not require registration with the United States Department of the Treasury Alcohol and Tobacco Tax and Trade Bureau.The vast majority of Napa County is covered by the boundaries of the world-famous Napa Valley AVA, an American Viticultural Area, and its various sub-appellations.