MSM math: when it’s a liberal cause use vague number such as ‘dozens’ or ‘hundreds’ and make sure you describe them as ‘vocal’ or ‘energized.’
When it’s conservatives or just plain old taxpayers rely on police estimates and make sure you discount attendance by making sure to mention children and old folks.
While I have absolutely no experience in estimating crowd sizes, I would have put the attendance # at 1000-1500. People were arriving as well as leaving throughout the time I was there. I had to leave shortly before noon to get back to work.