San Mateo County, CA Sign Regulations: Political Signs (2026)

San Mateo County's Development Code (formerly Zoning Regulations) regulates signs primarily through district-specific sign standards rather than a separate political-sign ordinance, and it does not impose a distinct size or duration limit on political/campaign signs as a separate category in the unincorporated zoning code reviewed. Under U.S. Supreme Court precedent (Reed v. Town of Gilbert), governments generally cannot regulate signs based on their political content, so temporary political signs on private property are broadly protected speech subject only to content-neutral time, place, and manner rules. The clearest enforceable state standard applies near state highways: California Business and Professions Code Section 5405.3 (Outdoor Advertising Act) provides that a temporary political sign may be no larger than 32 square feet, may be placed no sooner than 90 days before the scheduled election, and must be removed within 10 days after the election. Political signs may not be placed within highway rights-of-way or within 660 feet of a landscaped freeway where visible from the roadway. Off-premises and abandoned signs are listed among prohibited signs in several County zoning district sign standards. Residents should place signs on their own property and avoid the public right-of-way.