Conversation so far:
when did cars become more common than horses
In NYC the tipping point was 1908. In 1908 the number of cars passed the number of horses for the first time.
What made people start buying cars instead of horses?
Mass production of the automobile brought its price within the reach of the working class.

Question: What did people do before then?
Self-contained rewrite: What did the working class use for transport before the automobile?