How big was the 9/12 crowd

I thought this article did a good job of estimating the crowd

Rumored number:  2 million
"People Meter" count: 1.5 million
Eight Pennsylvania Avenues full of people:  800,000
Grand Memorial Park full of people:  250,000
Media estimates:  70,000

Boy, that 70,000 sure stands out, doesn't it... read the article for a description of the above numbers.