How Many People Attended the 9/12 March in DC?

Reader David Thomasson writes in:

Here's one way to think about it: Those who estimated 60,000 to 70,000 would have us believe that if a capacity crowd from the Orange Bowl would fill the yellow areas shown here.

He supplies this schematic, which suggests far more than the 75,000 estimate floating out there:

Other attempts at estimating the crowd size include Rand Simberg's two calculations that are very interesting and yield ranges from around 250,000 to 500,000. Hat tip: Mark Hemingway at The Corner.

And there's this Pajamas Media analysis, which yields an estimate of 850,000, the same number apparently that actually showed up for Obama's inauguration (after initial reports of 2 million). Having been in DC for both the 9/12 march and Obama's swearing-in, there's no question the latter event was much, much more populated. The article is very interesting for its history of estimates of attendance of Mall events.

I don't feel like I've got a real handle on numbers and estimates like this, but those lower six-figure figures (anywhere from 100,000 to about 250,000) seem to be pretty plausible.