Or one reason, anyway. From Robert Caro, who wrote a book about public sector transportation magnate Robert Moses (boldface mine):

I remember his [Moses’] aide, Sid Shapiro, who I spent a lot of time getting to talk to me, he finally talked to me. And he had this quote that I’ve never forgotten. He said Moses didn’t want poor people, particularly poor people of color, to use Jones Beach, so they had legislation passed forbidding the use of buses on parkways.

Then he had this quote, and I can still he him saying it to me. “Legislation can always be changed. It’s very hard to tear down a bridge once it’s up.” So he built 180 or 170 bridges too low for buses.

We used Jones Beach a lot, because I used to work the night shift for the first couple of years, so I’d sleep til 12 and then we’d go down and spend a lot of afternoons at the beach. It never occurred to me that there weren’t any black people at the beach.

So Ina and I went to the main parking lot, that huge 10,000-car lot. We stood there with steno pads, and we had three columns: Whites, Blacks, Others. And I still remember that first column—there were a few Others, and almost no Blacks. The Whites would go on to the next page. I said, God, this is what Robert Moses did. This is how you can shape a metropolis for generations.

Yes, one reason I write about transportation is because it affects me. But how we get from place to place–as well as how we can’t–is such a critical part of our lives. It shapes everything: who we live with, go to school with, what kinds of opportunities we get, who really gets to use public spaces.

It does matter.