This polygon shapefile depicts the active parcels, including physical addresses, over which the County of San Mateo holds authority. A parcel is a piece of real property under a defined ownership, or it can be a lot in a subdivision. County governments administer and legislate through the creation of and maintenance of land records that are associated with a parcel of land. Thus the parcel is often the vital administrative unit of local government. Parcel maps must meet the requirements of the General Plan and all applicable laws and ordinances. Parcel maps are alternately called tax maps, plat maps, plot maps and assessor maps. This layer is part of a collection of GIS data for San Mateo County, California.This coverage can be used for basic applications such as viewing, querying, and map output production, or to provide a basemap to support graphical overlays and analyses of geospatial data.