The block heater plugs into 110 volts, to keep the engine from freezing overnight in extreme climates, or just to make it easier to start on very cold mornings. In some parts of Alaska and Minnesota temperatures can get as low as -60 F (-50 C) which will freeze regular anti-freeze.

I not aware that any USA vehicles that came factory with block heaters, although I expect they are dealer-fitted to cars sold in Alaska. I've seen a few here in Washington State, especially from the desert regions of eastern Washington, but they are owner-added. Seattle is protected from the Arctic air by high mountains (4000 m) to the east and the ocean at the west keeps things from freezing.