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District police officials suggested then that about 100,000 attended, and although some organizers agreed, they have since put the number closer to 200,000. This time, they said, the turnout was 500,000. Metropolitan Police Chief Charles H. Ramsey said he would not provide an estimate, but said it was bigger than October's. "It's one of the biggest ones we've had, certainly in recent times," he said.
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Regardless of the exact number, the crowd today on the Mall was the largest anti-war demonstration here since the Vietnam era. People packed much of four long blocks of the Mall, shoulder-to-shoulder in many sections, from 3rd to 7th streets SW between Madison and Jefferson drives for the 11 a.m. rally. The first marchers stepped off at about 1:30 p.m., and when many had begun reaching the Navy Yard more than two dozen blocks away about an hour later, protesters were still leaving the rally site.
Who knows what the real number is, but minimum estimates for October were 100,000 so we can assume it was at least 150K or more. Not bad for a frigid January day.