This isn't the first step toward electrifying mass transit in the LA area, but is one of the larger examples. The DOT unveiled just four buses at the start of 2017, for example, so this is certainly a much larger commitment. And notably, it's not just from an American company -- it's from a company whose manufacturing is even located in the county. The region's Metropolitan Transportation Authority bought 95 buses in July, but they were split between Chinese transportation giant BYD and the American division of Canada's New Flyer.

It'd represent a big order for Proterra as well. At the start of 2017, it had received 375 bus orders. This is a big deal for a firm that's still hitting its stride, and shows that it's earning the trust of some major cities. Don't be surprised if its buses become more of a mainstay going forward.