1. “This is about health, it’s about life and death.”

That was Gov. Jerry Brown of California, announcing a lawsuit against the Trump administration over car emissions rules. Above, an interchange in Los Angeles.

California is leading a coalition of 17 other states and the District of Columbia in the suit, arguing that the Environmental Protection Agency’s effort to weaken auto emissions rules is unlawful. They’re also accusing the agency of violating the Clean Air Act.

The suit brings the American auto industry closer to a split into two markets, an outcome automakers are scrambling to avert.