When this parade took place, it was part of some sort of event which included a race. Apparently one car reached the speed of 70 miles an hour. That's not much for these days, of course, but stop and think that thirty years later, Burma Shave was putting up its famous signs to be read on major inter-city highways, where the traffic proceeded at a roaring 30 miles and hour. Add in the knowledge that in 1901, this was suburban territory, and think about how you'd feel if a car was rolling down Main Street or Railroad Avenue at 70 miles an hour!
It was after this time that the auto industry invented the term "jay walker". I've seen citations as early as 1905. That's what the auto industry called people who thought they had a right to walk in the street, as they had been for thousands of years.