Codes: California has already embraced 2012 versions of residential and energy conservation codes. Many other states and localities still are fighting over whether to accept 2009 standards.

Water: California’s water rules were a model for federal clean water statutes and remain tougher in such areas as controlling mud and water runoff from building sites.

Vehicles: California Air Resource Board regulations on truck particulate emissions are forcing dealers to curb idling and replace vehicles earlier than owners in other states would.

Chemicals: California stands virtually alone in Proposition 65’s requirements that dealers post signs notifying customers of the presence in yards of potentially cancer-causing substances—even wood dust.

Fires: San Diego County and nearby jurisdictions are quickly becoming as authoritative a source on building and material standards involving wildfires as Florida’s Miami-Dade County is on hurricanes.

Regulators: California’s state agencies have a reputation for striking out on their own on standards, long before the federal government or other states move.

— Brendan Rimetz