It's easy to forget stuff like this:

In the first decade of the 20th century there were no stop signs, warning signs, traffic lights, traffic cops, driver's education, lane lines, street lighting, brake lights, driver's licenses or posted speed limits. Our current method of making a left turn was not known, and drinking-and-driving was not considered a serious crime.

There was little understanding of speed. A driver training bulletin called "Sportsmanlike Driving" had to explain velocity and centrifugal force and why when drivers took corners at high speed their cars skidded or sometimes "turned turtle" (flipped over).

The transition from horses and buggies to horseless carriages, as they were first called, was one of the most impactful things to ever happen to our cities. Cars were more dangerous. Some, or perhaps many, were opposed to them initially (and didn't see the need to move away from horse-drawn wagons). And we had to invent a myriad of traffic systems in order to try and make them remotely safe for people.

One could easily argue that we are still grappling with these same safety problems.