I ran along Adams, and Michigan Avenue, had a long stretch on Columbus (where I've finished the Chicago Triathlon twice). The Columbus stretch was pretty fast - no cars. As I headed back I knew it was close. I hit the 19:00 mark at just shy of thee miles. I was almost there.
The phone Strava GPS is a little delayed and I looked down at 3.1 miles and 19:52. I'd later realize that I really ran the 5k in 19:48. I'm very pleased with that.