Napa Valley AVA is an American Viticultural Area located in Napa County, California, USA. Napa Valley is widely considered one of the top wine regions in California, and all of the United States, with a history dating back to the nineteenth century. The combination of Mediterranean climate, geography and geology of the valley are conducive to growing quality wine grapes. John Patchett established the valley's first commercial vineyard in 1858. In 1861 Charles Krug established Napa Valley's first commercial winery in St. Helena. Viticulture in Napa suffered several setbacks in the late 1800s and early 1900s, including an outbreak of the vine disease phylloxera, the legal institution of Prohibition, and the Great Depression. The wine industry in Napa Valley recovered, and helped by the results of the Paris Wine Tasting of 1976, came to be seen as capable of producing world-class wine. Almost 4.7 million people visit Napa Valley each year, making it the second most popular tourist destination in California, second only to Disneyland.