Why Are There Two Emissions Standards for Vehicles in the US?


One of the plainest examples of the US federal system at work is emissions standards. There are essentially two standards for vehicle emissions in the US: federally mandated standards that all states follow and the stricter standard set by California.

For the most part, states follow one of these two standards. But why are some states more strict about emissions than others? Two things are at play here: how much traffic there is in LA and how the federal system in the US works.

Federal System

The federal system is simple to explain but hard to understand in practice. Essentially, the federal government handles national laws and makes regulations that apply to all 50 states. However, the states are also free to pass their own laws, within some limitations based on the language of the Constitution.

This system is messy in practice, though. Often, the Supreme Court has to get involved to resolve disputes between states and the federal government when their laws are at odds with one another. However, generally speaking, states are free to enact stricter laws than the federal government. That’s exactly what California did in 1967 when the state created the California Air Resource Board.

California’s Standards

Three years later, the federal government created the Environmental Protection Agency to help rein in emissions across the country. However, California was given a special dispensation by the federal government to continue following its preexisting, stricter emissions standards. Those standards were critical for the state, as the extremely dense population of Los Angeles County had led to immense amounts of smog in the region by the late 60s.

Other states with dense populations have also adopted California’s standards, getting special permission from the federal government to follow the Golden State’s example. States that follow this standard are often called “CARB states,” and people living there need to submit their vehicles for emissions tests and could even pay fines if their vehicles are compliant with the standards in place there.

People who live in non-CARB states often find the rules and regulations in place in CARB states to be surprising. Owning a car is already expensive enough that people rely on oil changing coupons and carpooling to avoid some recurring costs. Adding in fines that push drivers into newer, more expensive cars makes those cost-saving measures even more important for people living in CARB states. It’s either that or buying an all-electric vehicle!