27 : cops! on horses!
At each point where particularly radical pro-life folk were gathered to counter protest (though, in comparison, they looked less like a protest and more like a couple of guys standing on a corner), there were mounted police.
When nothing was going on, which was most of the time, the police would let protestors and their kids pet the horses. They were super sweet, these cops.
While there were definitely some raving counter-protestors (some of whom, I learned later, were arrested for nasty things like carrying around jars of fetus parts and shoving them at people), it felt the whole time like things were under control. Thanks to the cops and the organizers/volunteers for that.