Currently, very little is known about the locations of the set of filming, and where the show was based.
Agrestic/Majestic/Regrestic.
The filming of Agrestic, California (Which later becomes Majestic in an attempt to merge the two cities, and eventually becomes Regrestic.) is based off of the Los Angeles suburb Stevenson Ranch, California. Some scenes from the area, are filmed and take place in Santa Clarita, California.
Ren-mar
The filming and shooting of the area Ren-mar where Nancy, Andy, Shane, and Silas Botwin travel after Nancy burns their house down during a valley fire in Majestic in order to clear their previous lifestyle. Ren-mar is a fictional small beach town in the San Diego area. Ren-mar is filmed in the beachside Los Angeles Suburb Manhatten Beach