Back in the 1970s when I was in my 30s and running well, I lived in Buffalo. The distance around the most popular park (Delaware Park) was known, and because enough races were run in the park there were start and finish marks (all on certified courses) and a lot of accurate but uncertified distances as well. Actually I remember that one loop around the park was certified and thus could be used for longer races, where I just counted up the number of laps I needed and then added whatever offset was necessary.
(At the time, I was the chief course measurer in the area and would lay down marks of convenience if people wanted them, using a calibrated bicycle -- always on the curb in brown paint, just a mark, so you did have to know which mark it was, but most of the serious runners did.)
In those days, too, there were bicycle odometers (CatEye was a common one), and with some simple calibration they were plenty good enough to get a distance that wouldn't be off by more than a few dozen yards, if that.
Also, the courses for many of the road races were near the park, or used part of the park, so you could jump onto a race course, many of which had the same discreet marks every mile. And the Skylon Marathon start was near the park, so you could run an out-and-back along the marathon course if you wanted to.
Urban running has its drawbacks, but Buffalo was an amazing urban running site.