The Historical View of the Baylands is a composite picture based upon approximately 1000 independent sources of data. These include eighteenth- and nineteenth-century maps, sketches, paintings, photographs, engineering reports, oral histories, explorers' journals, missionary texts, hunting magazines, interviews with living elders, and other sources. Sufficient information about the early Bay Area landscape is available from early European documents to discover the distribution and abundance of many habitat types with confidence. With a robust amount of data, historical sources overlap and confirm (or contradict) each other, strengthening their interpretation. The intersection of discrete sources is then mapped and recorded in a database. This file represents historical riparian area polygons derived from this process.