Update: As was noted in the comments, the picture below in the original post is of the wrong rally. This ground-level picture of the rally clearly shows that it didn’t take place on the mall nearly as extensively as the image I mistakenly posted does.
Even based on that image, however, I feel the National Park Service’s graph holds up. I don’t think the 1,000,000 figure for the tea party is at all inappropriate.
Maybe this will finally put some of the speculation about the size of the DC tea party into perspective (click for a larger view):
Couple that with this graphic used to measure Obama’s inauguration numbers published by the USA Today and the National Park Service:
That graphic estimates crowd size going almost back to the Washington Monument as being about 1,000,000. The tea party crowd didn’t go up as close to the capitol as the Obama inauguration crowd did, but the tea party crowd also went all the way back to and around the Washington Monument.
I don’t think a crowd size of 1,000,000 is an unreasonable estimate.