This polygonal dataset shows the spheres of influence for all incorporated cities within Butte County, California. The layer should not be used as the official sphere of influence boundary.What's a Sphere of Influence? A Sphere of Influence designates an agency's probable future physical boundary and service area. It is territory that a city or special district will annex in the future. It's also the area where the local government will build facilities and deliver services sometime in the future. A sphere of influence is often bigger than a local government's current jurisdiction. http://www.calafco.org/docs/TimetoDrawLine_03.pdf)