What Will Happen to Public Transit in a World Full of Autonomous Cars?

The great promise of autonomous cars is not that we could each own one in our own driveway – the 21st century's version of owning your own Model T, or your own color TV, or your own bulky Macintosh – but that no one would need to own one at all.

That's because when cars can drive themselves, they can drive off when we're done with them. They can pick up other people instead of sitting parked outside. We'll request them on-demand. They'll pull up out front, take us right where we want to go, then do the same thing for a hundred other passengers, a hundred times over. They'll behave, in other words, like sophisticated ride-share services – or like personalized mass transit.