Most development within incorporated cities like Tucson, South Tucson, and Sahuarita is handled by those respective city governments for permitting and zoning. The Pima County Development Services Department handles unincorporated areas. Pima County has specific overlays for flood hazard areas and fire-prone regions that may require additional review.
How this fits with the state
The state authority here is Arizona Registrar of Contractors. The county file does not replace that — it adds the permit office, local overlays, and the actual filing path.