Sonoma County

The Sonoma County dataset represents the largest political/jurisdictional boundary of local government within the State of California, United States of America (USA).  Sonoma County took official formation in 1850 and did not take formation from a "parent county" (e.g. a subset political/jurisdictional of a larger geographical region within California).

Historical notes:

On February 18, 1850, California's first Governor, Peter Burnett, signed into law the creation of the state's 27 original counties which included Sonoma County.  (Note: On September 9, 1850, California became the State of California with the original twenty-seven counties.)

Original county boundaries often followed geographic features such as mountain ridges.  In the middle of the last half of the nineteenth century many of these boundaries were changed slightly so that they now run along township lines and section lines. Sonoma County is one of the original 27 counties. Most of Sonoma County has been in the county since 1850 yet the present territory has three histories: 1) territory was in Mendocino County from 1850 to 1855, when it was added to Sonoma County, 2) territory was in Mendocino County from 1850 to 1859 when it was added to Sonoma County, and 3) Sonoma County had administered Mendocino County from 1850 to 1859; territory which at one time was in Sonoma County is now in Mendocino, Napa, and Solano Counties. 

Sonoma County was named after "Sonoma" which is a Chocuyen Indian name translated by some as "Valley of the Moon" and by others as "land or tribe of the Chief Nose."

Since the GIS data was developed for planning purposes and use in publication of maps and/or database creation, the data is for illustrative purpose only and is not suitable for parcel specific decision making. 

Therefore, the GIS data presented herein are approximations and further land development determination is at the discretion of the PRMD planning staff which may require a parcel specific site review (to draw parcel specific conclusions).

Creation methodology & resources:
1) refer to Data Quality - Attribute Accuracy tab for historical dataset modifications by ActiveMap version release number
2) for ActiveMap Data Capture June 2010 [ver. 2.0.2], no edits needed to rectify dataset to AM_PARCEL 04/01/2010 (no modification to borders of changed parcels & validated topology)