Minnesota's new vehicle emissions standards will go into effect next year.
This comes after the US Supreme Court refused to take up a lawsuit that would have delayed implementation.
The law mirrors the tailpipe emissions standards now in place in California.
The suit was filed by Minnesota auto dealers, who claimed the state does not have California's smog problem.
The new standards also requires auto dealers to increase their stock of electric and hybrid cars.
In a statement, Minnesota auto dealers president Scott Lambert says they should not have to stock vehicles that have little demand.