By that definition (the possibility of annihilation) I only count two - the Cold War and the American Civil War. I don't like the definition, though - the US certainly was at war in WWII.
Somewhat unrelated, but I'd really like to see the War Powers Resolution get to the Supreme Court. It would be nice to either have it acted upon or thrown out instead of having it just sit there being ignored.
The cold war didn't kill many Americans, it was mostly about Americans killing Latin Americans or Koreans or Vietnamese or Laotians or Cambodians either directly by napalm or by puppet dictators that were installed after CIA-backed coups, such as the original 9/11: the 9/11/1973 coup against President Allende of Chile (or 1953 Iran or 1954 Guatemala or 1964 Brazil).
The Russians weren't in Cuba for no reason, we were in their backyard before they started their attempts to close the "doomsday gap" (quoting that term from Dr. Strangelove).
Quoting Blum:
Let's also not forget that Eastern Europe became communist because Hitler, with the approval of the West, used it as a highway to reach the Soviet Union to wipe out Bolshevism forever, and that the Russians in World War I and II, lost about 40 million people because the West had used this highway to invade Russia. It should not be surprising that after World War II the Soviet Union was determined to close down the highway.
Somewhat unrelated, but I'd really like to see the War Powers Resolution get to the Supreme Court. It would be nice to either have it acted upon or thrown out instead of having it just sit there being ignored.