Use stattistics to Lie wrote:
Stats people have corroborated 3,000,000 at the Tournament of Roses Parade, the largest yearly gathering in the US. They looked at hotel occupancy, rental cars, airline flights, gasoline sales, fast food sales figues, etc. to correspond to claims.
The 3M figure is for the the entire 72 hour New Year's celebration as well as the Rose Parade, and not just the parade itself. Some people don't stay for both.