While more than 40 states have their own local wine industry, only California, Oregon and Washington really have more than an in-state or even regional following. New York can make a claim for national business, but it is a fading position. In the days before the development of California as the country's wine powerhouse, New York (and even Ohio) wines had wide scale distribution but that has largely disappeared except in the East. Wines from up and coming wine producing states like Texas are still curiosities in most of the country.
The wines from California have clearly surpassed those of other states in terms of 'share of mind' and 'share of market'. They can be found to some degree in nearly every country of the world. The climate is so consistent in much of California that there is rarely a problem getting enough sun to mature the grapes. In fact, the ability to fully ripen the crop year after year has led to a style of wines that is generalized as 'over the top' with regard to fruit flavors, and the use of too much oak as a counterpoint to the forward fruit. While this style is certainly to be found in some wineries, many others are producing wines with subtle complex flavors and appropriate acids.
Several regions of California have shown an ability to grow fine grapes for winemaking but none have reached the renown of the Napa Valley (and Sonoma County as first runner-up). These two counties have most of their agricultural efforts devoted to growing grapes for wine.
In general, California's coastal counties produce the best wines while the large hot central valley grows great quantities of grapes that almost never reach the higher rungs of quality. The central valley grapes are used mostly by the big, bulk producers for everyday table wines.
Over the last few years, the various parts of the US have made an effort to begin to classify the different wine growing regions into appellations. These do not indicate any particular quality or lack of it. The appellations only indicate growing areas that have particular gorwing conditions due to the local climate or geography. To see a list of specific approved American Appellations, click on the link below: