To identify the largest vineyard owners in Sonoma County, The Press Democrat analyzed land records on 3,171 vineyard properties obtained from the Sonoma County Assessor's Office, which were updated in August 2013. It excludes non-vineyard properties owned by those companies.

The locations of the vineyard parcels were mapped using GIS data from the Sonoma County Information Systems Department.

Search our interactive map of Sonoma County vineyards here

Ownership groups that hold properties under multiple names were identified by interviews with wine industry sources and a Press Democrat analysis of property tax data from the Assessor's Office and pesticide application reports filed with the Sonoma County Agricultural Commissioner's Office.

The group "Jackson Family Wines & Affiliates" includes properties owned by Jackson Family Wines and its affiliated companies, executives and family members.