Earlier quoted context omitted.
The automobile did not clean up the streets. The personal automobile was much too expensive for that. Buses and trams and metros and transport trucks and railways and bicycles cleaned up the streets. The average person didn't own a car and use it daily until much after the streets "cleaned up".
Do you have some references for this bold statement? The development of busses, trams, metros etc increased urban traffic (much as widening highways increases traffic, and traffic jams) including animal-drawn traffic, at least in the cities where I have read up on the history of urban transportation (in particular London, Paris, and New York). The GP mentioned Mumbai, which only recently banned animal traffic. It was…
Until the late 50s, most households in the US did not have a car : https://oldurbanist.blogspot.com/2013/02/was-rise-of-car-own...
Without a car, the only solution is public transport. And public transport in early 20th century America was the dominant source of the use of animals in personal transport.
The confounding factor here is transport, hence why I mentioned trucks. Go to for example Tiznit in Morocco and observe how animals are used. They're not used for personal transport - they're not efficient for that in city environment - their use is moving merchandise.
