CARB states are the jurisdictions that have adopted California’s stricter vehicle emission standards in place of the federal baseline set by the EPA. As of 2025, seventeen states plus the District of Columbia follow rules written by the California Air Resources Board for at least some categories of vehicles. If you live in one, the cars and trucks sold to you must meet tighter pollution limits, you get longer warranty coverage on emission parts, and low-mileage vehicles bought out of state can be refused registration.
Which States Are CARB States
The states that have adopted California’s vehicle emission program, along with the District of Columbia, fall into a few groups.
The long-standing members, which adopted California’s low-emission vehicle standards between 2004 and 2007, are New York, Massachusetts, Vermont, Maine, Connecticut, Rhode Island, Oregon, Washington, New Jersey, Pennsylvania, and Maryland.1Alternative Fuels Data Center. Adoption of California’s Clean Vehicle Standards by State
More recent adopters are Delaware, Colorado, the District of Columbia, Minnesota, Nevada, New Mexico, and Virginia.1Alternative Fuels Data Center. Adoption of California’s Clean Vehicle Standards by State
Arizona and Florida once adopted the California standards and later withdrew.
Virginia’s status is unsettled. A 2021 law tied the state to California’s emission program. In 2024, Governor Youngkin announced Virginia would stop following CARB rules, but the Democrat-controlled legislature blocked legislative repeal, and the legal picture remains unresolved.
Not every CARB state has adopted every California rule. Some follow only the passenger vehicle standards, some add the zero-emission vehicle mandate, and a smaller group has also adopted the commercial truck program. What applies to you depends on which pieces your state signed up for.
Why California Sets Its Own Standards and How Other States Join
The federal Clean Air Act generally forbids states from writing their own tailpipe emission rules for new vehicles. California is the single exception. Under 42 U.S.C. § 7543, the EPA must grant California a waiver to enforce its own standards so long as those standards are at least as protective as the federal ones and address “compelling and extraordinary conditions.”2Office of the Law Revision Counsel. 42 USC 7543 – State Standards The state earned this position because it was already regulating vehicle pollution before Washington entered the field, driven by smog in the Los Angeles basin.
Every other state then has a choice under Section 177 of the Clean Air Act, codified at 42 U.S.C. § 7507: follow the federal EPA standards or adopt California’s. There is no third option. A state opting in must adopt rules “identical to the California standards for which a waiver has been granted” and do so at least two years before the affected model year begins.3Office of the Law Revision Counsel. 42 USC 7507 – New Motor Vehicle Emission Standards in Nonattainment Areas The two-year lead time gives automakers and dealers notice to stock compliant vehicles.
The identicality requirement matters. A state cannot cherry-pick pieces of California’s program or tweak the rules, because that would create an illegal “third standard” and trigger federal preemption. Automakers, in turn, only ever have to build for two regimes: federal and California.
What CARB Rules Mean When You Buy a Car
The distinction that matters at the dealership is between “50-state legal” and “49-state legal” vehicles. A 50-state car meets both federal and California standards and can be registered anywhere. A 49-state car meets only the federal rules and can be refused registration in a CARB state if it is treated as new.
The line between new and used is drawn at mileage. Under California’s regulation, a vehicle with fewer than 7,500 miles on the odometer is legally treated as new, and a new vehicle must be certified by CARB to be registered.4Cornell Law Institute. California Code of Regulations Title 13 Section 151.00 – Refusal of Registration The rule exists to stop buyers from driving to a non-CARB state, buying a cheaper, non-compliant car, and bringing it home. Other Section 177 states generally follow the same framework, though specific thresholds and enforcement can differ.
You can check compliance in two places. The underhood emission control label states whether the vehicle conforms to California regulations or is certified for all 50 states. For new vehicles, the Manufacturer’s Certificate of Origin carries the same information. If either says the car is California-certified or 50-state legal, you can register it.
If you already own a higher-mileage vehicle that meets only federal standards and you move into a CARB state, the picture is easier. The 7,500-mile threshold targets low-mileage vehicles that are functionally new. A used vehicle over that mileage can typically be registered, though it will still have to pass whatever smog or emissions inspection the state requires. Testing frequency varies, with most states inspecting either every year or every two years, and fees run from nothing to around $90.
A vehicle that cannot meet the applicable requirements can be refused registration outright.4Cornell Law Institute. California Code of Regulations Title 13 Section 151.00 – Refusal of Registration The rule also prohibits driving or selling a non-certified new vehicle as a workaround. If it cannot pass, it cannot legally be driven in the state until either the vehicle is brought into compliance or the mileage threshold no longer treats it as new.
Longer Emissions Warranty Coverage
A benefit of buying in a CARB state that often gets missed: emission-related components carry longer warranties than federal law requires. The coverage tiers are:
- Standard emission parts: 3 years or 50,000 miles for defects and performance on all emission-related components.
- High-cost emission parts: 7 years or 70,000 miles for expensive components like catalytic converters, engine control modules, and other parts specifically listed in the owner’s manual.
- PZEV and TZEV vehicles: 15 years or 150,000 miles on emission-related parts, with the battery or energy storage device covered for 10 years or 150,000 miles.5California Air Resources Board. California Vehicle and Emissions Warranty Periods
The PZEV and TZEV tier is where CARB residents gain the most. If a catalytic converter fails at 120,000 miles on a Transitional Zero Emission Vehicle, the manufacturer pays. Under the federal warranty alone, that repair would fall on the owner after 70,000 miles. If you are shopping used, check the underhood label for PZEV or TZEV certification.
Zero-Emission Vehicle Sales Targets (And Why They May Not Apply)
The biggest recent change in CARB states is Advanced Clean Cars II, adopted by California in 2022. The rule requires escalating zero-emission vehicle sales: 35 percent of new passenger cars and light trucks sold for model year 2026, rising to 68 percent by 2030 and 100 percent by 2035. Plug-in hybrids count if they can travel at least 50 miles on electric power alone, and they can cover no more than 20 percent of a manufacturer’s ZEV compliance. Qualifying battery-electric and hydrogen fuel cell vehicles must have at least 150 miles of range and include fast-charging capability.6California Air Resources Board. California Moves to Accelerate to 100% New Zero-Emission Vehicle Sales by 2035
States that formally adopted ACC II include California, Colorado, Delaware, Maryland, Massachusetts, New Jersey, New Mexico, New York, Oregon, Vermont, Virginia, and Washington. States that adopted in 2023 would see requirements begin with model year 2027 rather than 2026 because of the two-year lead time.
Whether these sales targets will actually be enforced is unsettled. In May 2025, Congress passed three Congressional Review Act resolutions nullifying the EPA waivers behind Advanced Clean Cars II, the Advanced Clean Trucks rule for commercial vehicles, and the Omnibus Low NOx heavy-duty regulation. California and other states sued almost immediately. The Congressional Review Act also bars the EPA from issuing future rules “substantially the same” as the disapproved waivers without new authorizing legislation. If the nullifications stand, California loses authority to enforce those standards, and every Section 177 state that adopted them loses the legal basis for enforcement too. The consumer effect would be a return to federal emission standards in CARB states, with no state ZEV sales mandate for automakers to meet.
The Advanced Clean Trucks rule, adopted by eleven states, is on the same footing. Several of those states, including Massachusetts, Oregon, Vermont, and Maryland, had already delayed enforcement into model year 2027 or later on their own before the congressional action, citing concerns about the availability and cost of zero-emission commercial trucks.