As you can see in the video below, Beck was on his network's morning show, "Fox & Friends," on Tuesday, where he was repeating some particularly outlandish claims. He dismissed what he called the "official" estimates putting the crowd at 60,00-75,000 people (actually, that was an unofficial estimate, but I think it's more interesting that Beck so casually dismisses facts when he's got his own preferred version) saying, "Of course everybody was saying tens of thousands, because that's the 'official' report. If you look at the pictures, university looked at it, did the body count ... 1.7 million."
What university was this that provided the estimate? (And since when does a university, the institution, do that? Shouldn't it be a single professor, hopefuly someone who actually knows something about estimating crowd sizes rather than, say, a law professor who happens to be a blogger?) Beck couldn't remember.
Beyond all the other reasons I've already laid out that you shouldn't believe this claim, here's a really good one: If 1.7 million people had indeed showed up, that would have made the event one of the biggest gatherings in D.C. history, if not the biggest -- potentially larger, even, than President Obama's inauguration. The inauguration filled the mall and shut down the city; this protest didn't come close to doing either.