The crowd for Friday's Stanley Cup parade and rally was huge by any measure, but at least one statistician says the city's official estimate of two million attendees is a bit overzealous.

"Most censuses of Chicago give you three million people for Chicago," said Stephen Stiegler, the Chairman of the Department of Statistics at the University of Chicago.  "Do you really believe that two-thirds of Chicago was down there?  No!"

The official parade route was about 30 blocks long, beginning at the United Center and heading down Madison Street to Ogden Avenue to Washington and Wacker.  There, the caravan of double-decker buses and trolleys traveled east on Washington Avenue to  Michigan Avenue and then north on Michigan to Wacker, where a staging area was setup.

When plans were initially announced Wednesday evening, the city said it expected about 350,000 people to line the route, but city officials revised that number Friday, inflating it to almost six-times that number.

"We know the exact length of the route and the blocks. We know how many people can fit on a block.  We know from the White Sox parade in 2005, after doing all of that research.  And we have a lot of aerial photos.  There's an actual science to it," said Jen Kramer, the Director of Sports for the Mayor's Office of Special Events. 

But, "it's an estimate," she clarified, coordinated with police, the Office of Emergency Management and Communications and the mayor's office.  Turnstiles aren't used for events like this, she says, so there's no way to ascertain a firm tally.

The city's best guess for the entire 2005 White Sox celebration put the crowd at 1.2 million and "this was, hands down, well above and beyond that," Kramer said.

Still, the city's estimate doesn't fly with Stiegler.  He looked at an aerial photo of one third of a city block, and by estimating the number of people he saw, and then multiplying that number by how many equal portions of the city were covered by people, came up with a much lower estimate:  400,000. 

It's certainly not the first time such an estimate would be challenged.  In 1979, the Papal mass at Grant Park was estimated at one million but reconnaissance experts later knocked that figure down to somewhere between 65,000 and 350,000 people.  And the number of people who attended President Barack Obama's inauguration last year ranged from one million to five million.

"Most people look at a crowd like that, and they say, 'Boy, there are a lot of people there.'  Most people have no incentive to underestimate," Stiegler said.  "If you're in the business of crowd control, you want to brag about how much you've controlled.  If you're in the business of puffing up the Blackhawks, which don't need any -- they're so great this year -- then you aim for a big number."

It's not that Stiegler wants to rain on anyone's... well, parade... it's just that he doesn't think the city's estimate is statistically possible.

"You're going to have a pretty large margin of error no matter what you do, but not by a million," he said.

Full Coverage:  The Blackhawks' Run for the Cup