Why is Cider not Sparkling in the USA?

This is something that has confounded me for twenty years. In America cider is not sparkling. Even cider that is imported directly from the UK (eg: Strongbow, Dry Blackthorn) is flat. Why is this? I’m guessing it is something to do with the sparkling wine (“champagne”) lobbyists, but I really don’t know for sure. Cider without the sparkle is just not the same.