Despite how famous the counties of Napa and Sonoma are for the quality of wines that come out of them, together they produce less than ten per cent of the grapes used to make California wines. Most of California’s wine grapes come from the Central Valley. This region grew seventy per cent of the wine grape harvest in California in 2018. Napa and Sonoma are known for their quality, not quantity. There are great wines that come out of all regions, but these two became famous for their exceptional product.