Oltion, Jerry. "Red Alert"
Divergence: 1520 CE
What if: Montezuma kicked the Spaniards out of Mexico and North AmerInds had similar success, leaving only the European colony on Manhattan Island.
Summary: The Cuban Missile Crisis, recast in the 1800s as the Iroquois Federation inter-tribal air force vs. Manhattan.
Published: In Analog, October 1991; and What Might Have Been? Volume 4: Alternate Americas (eds. Gregory Benford and Martin H. Greenberg), q.v.