This bill requires cities receiving state infrastructure funding to allow duplexes and triplexes on any lot currently zoned for single-family housing. Cities retain control over setback requirements, height limits, and design review. The bill does not override historic district protections. Cities have 18 months to update local codes. Non-compliant cities lose 30% of their state infrastructure allocation. The bill includes $50M in planning grants to help smaller municipalities with code updates.