Curious because a story I'm working on revolves around a person driving a stolen car across the continental US. I don't want to set the story in a period where someone knowledgable would read it and say, "No way he could've gotten away with that."
I apologize in advance if this belongs in a different sub. Thanks in advance!
Probably the first was the discarding of the floor-mounted starter switch ( sometimes on the dash). The key switch was only for the ignition circuit. Not sure about the dates, but it was not uncommon on pickup trucks into the 1950's. With that, you could easily "hotwire" the ignition ( connect a short wire from the battery to the ignition coil) , step on the switch to turn over the engine, and drive away with the car. That could be done very quickly- there was not lot of stuff under the hoods of old cars, and so components were easy to locate.
After that, the next advance was the locking steering column. That happened in the '70's. Before then it was still possible to steer the car without the key, so if you could get the engine going ( hotwire the ignition, short the starter relay) you could drive.
Here's a Popular Science article on the subject in 1969.