The university is headquartered in the city of Berkeley in Alameda County, on the mainland side of the Bay of San Francisco, California. Additional branches are located in Los Angeles, San Francisco, San Diego and Davis. In 1880 it was decided to add viticulture and oenology as new branches. However, since Berkeley had too poor climatic conditions for viticulture, a branch was established in the interior of the country in the city of Davis (Davis is a common abbreviation for the viticulture branch). The then professor of agriculture, Eugene Hilgard, was one of several who noted the importance of grafting in the fight against phylloxera and the link between climate and the right grape variety. Prohibition (1920-1933) severely restricted the activities. Shortly after the lifting of the prohibition, in 1935, the Department of Viticulture was revived at the University. The focus was on the analysis of grape varieties and the training of the new generation of winegrowers.
In 1944, after extensive research, the Californian wine-growing regions were divided into five climate zones according to the so-called heat summation method (see the classification under California), with the scientist Albert J. Winkler (1894-1989) being particularly noteworthy. The oenologist and publicist Maynard A. Amerine (1911-1998) devoted himself to the study of the suitability of grape varieties for different climatic zones and the reconstruction of the viticultural knowledge lost through prohibition. Dr. Harold P. Olmo (1909-2006) became known through numerous new varieties and worldwide consulting activities. The grape specialist Dr. Carole Meredith clarified the origin of some grape varieties such as Cabernet Sauvignon, Syrah and Zinfandel using DNA analyses. At the university, Prof. Ann C. Noble (*1935) developed the so-called aroma wheel in the mid-1980s, in which wine aromas are divided into 12 main groups. Most of the viticulture and winery technology specialists working in California were and are trained in Davis.