The Tracy Hills AVA is an American Viticultural Area

American Viticultural Area

An American Viticultural Area is a designated wine grape-growing region in the United States distinguishable by geographic features, with boundaries defined by the Alcohol and Tobacco Tax and Trade Bureau , United States Department of the Treasury....

 located in both San Joaquin County

San Joaquin County, California

San Joaquin County is a county located in Central Valley of the U.S. state of California, just east of the San Francisco Bay Area. As of the 2010 census, the population was 685,306. The county seat is Stockton.-History:...

 and Stanislaus County

Stanislaus County, California

Stanislaus County is a county located in the Central Valley of the U.S. state of California. As the price of housing has increased in the San Francisco Bay Area, many people who work in the southern reaches of the Bay Area have opted for the longer commute and moved to Stanislaus County for the...

, California

California

California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...

. The 39200 acres (15,864 ha) region was designated an AVA as a result of a petition from the owners of Tulip Hill Winery in Lake County

Lake County, California

Lake County is a county located in the north central portion of the U.S. state of California, north of the San Francisco Bay Area. It takes its name from Clear Lake, the dominant geographic feature in the county and the largest natural lake wholly within California...

, who owned a vineyard

Vineyard

A vineyard is a plantation of grape-bearing vines, grown mainly for winemaking, but also raisins, table grapes and non-alcoholic grape juice...

 on Mount Oso

Mount Oso

Mount Oso is a mountain in Western Stanislaus County, located on theDiablo Range. At 3,360 feet in elevation, it is the third highest point in Stanislaus County. There are many radio stations and an unused forest fire lookout tower on the mountain...

 in the Tracy Hills. The five original vineyards in the appellation

Appellation

An appellation is a legally defined and protected geographical indication used to identify where the grapes for a wine were grown; other types of food often have appellations as well...

 are planted between 100 feet (30 m) and 500 feet (152 m) above sea level.