So, I was finally able to check the race site again and discovered that there were 20,588 finishers in yesterday's race; of these, I finished 9,305 - about halfway back. 12,021 of these finishers were women (that's many more women than men! obviously races are not the place to pick up boys . . . ), and of those I finished in place 3,737, just a third of the way back. I similarly finished #588 in my division (women aged 30-34), which had 1,573 participants in all.
The race has a costume contest every year, and some of the entrants were just excellent. See the link here. I also ran past Charlie Brown and some of the Superfriends. Superman, Wonderwoman, Batman, Robin, and who else? Is there a Supergirl? (I smoked the Superfriends. Gratifying.)