Historically speaking, officials (typically the police) lowball the numbers of participants at political protests and the organizers inflate them. So getting an exact count is always going to be problematic.
But a rough count is still worth the effort.
By the official count, the total in just four cities Saturday—Chicago, New York City, Los Angeles, and Washington, D.C.—was 1.3 million.
How many in your city? Chattanooga had 3,000. Omaha, 8,000. Morristown, N.J., 15,000. Denver, 50,000.