There could have been a lot more. The 1929 IND Second System expansion plan is depressing, especially the parts where provisions are already built:
- https://www.vanshnookenraggen.com/_index/2021/01/ind-second-...
- https://www.nycsubway.org/wiki/IND_Second_System_-_1929_Plan
If there were traffic laws, nobody knew them and people wouldn't know which way to go to avoid a head on collision.
If you'd just replace cars with horses today it would go a lot different.
And it wasn't just horses. It was horse-drawn carriages. There wasn't that much difference, traffic wise, between carriages and cars. There were traffic jams, out of control vehicles, drunk drivers, street racers, collisions, etc. all back in the 19th century.