San Diego County, CA
Data version: Q2 2026 · Last updated 2026-04-21
San Diego County is in California, home to 3,286,000 residents across 4,525 square miles. The county seat is San Diego. In most of California, zoning and building-permit authority sits with individual cities for incorporated areas; the county handles unincorporated parcels.
Cities in San Diego County with permit guides
This site currently publishes permit and zoning guides for 1 city inside San Diego County: San Diego. Each city has its own zoning code and permit process — pick the city to see local ADU rules, zoning breakdown, and permit timeline.
How zoning works in San Diego County
Zoning and permit authority in California is mostly local. Incorporated cities like San Diego run their own zoning codes, planning departments, and building inspectors. The county's planning department typically only handles unincorporated parcels, but counties set the framework for California state law compliance (ADU rules, wildfire hazard zones, flood plain overlays, subdivision requirements). The first question when screening any San Diego County parcel is always whether it sits inside city limits — that determines who your permit authority is.
County data sources
Population and land area for San Diego County are from the U.S. Census Bureau (2024 ACS estimates and Census Gazetteer). FIPS code 06073 follows the Census ANSI standard and matches the county's entry in every federal open-data system (FEMA NFHL, EPA Envirofacts, HUD, USGS).
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