Farouk El-Baz
Three days after the march, Farouk El-Baz, director of the Center for Remote Sensing at Boston University released a controversial estimate of 870,000 people with a margin of error of 25 percent, meaning that the crowd could have been as small as 655,000 or as large as 1.1 million. It later revised that figure to 837,000, with a 20% margin of error (669,600 to 1,004,400). The Park Service never retracted its estimate.