How do experts come up with crowd estimates at Washington events?
Crowd estimates in DC can be less than scientific. Case in point: Michele Bachmann’s count of 1.6 million people at Glenn Beck’s 2010 rally on the Mall. The real figure was closer to 87,000, says Curt Westergard of Digital Design & Imaging Service in Falls Church. His company estimates crowd sizes for CBS News by flying a camera-rigged balloon above the Mall. Here’s how it works.