The following estimates were taken from the US-IMC site, and related anti-war sites. The estimates vary widely and should be taken with a grain of salt in some cases, but the largest actions of the some 750 plus protests across the country on M-19 were in San Francisco, NYC, and L.A. None of these matched the turnouts reported from last year. The list below is only a partial sampling.

San Francisco: 10,000 plus - estimate from SF Bay IMC.
LA: 20,000 (ANSWER) - Hollywood, 2,000 estimate from LA IMC
NYC: 4000-10000 ( Harlem - Central Park) The Troops Out Now! action was the largest event in NYC, but a series of decentralized actions, including a die in at Times Square organized by the War Resisters League generated tremendous media coverage.
Seattle: 5-8000
Fayettteville: 4000
Minneapolis: 1,500
Pittsburgh: 3000
Chicago 2500-3000
Boston: Between 2-5,000
Miami: 1000
Milwaukee: 300
Nashville: 300
Houston: 2-300
Urbana-Champagin: several hundred

Check out US-IMC for additional reports at:
indymedia.us/en/index.shtml