In “Sullivan’s Travels,” Preston Sturges’ glorious 1941 comedy, a director of lightweight Hollywood fare (played with endearing earnestness by Joel McCrea), decides to hit the road, posing as a hobo, to make a socially relevant movie that explores the struggles of the Common Man: “O Brother, Where Art Thou?”

John Waters, the director who has made his share of lowbrow comedies, most famously the campy “Pink Flamingos” and “Hairspray,” recently traveled across the country on his own quest. Waters may not be quite as naive as Sullivan — he calls his trip his “hobo-homo journey,” after all — but his time on the road did open his eyes to the lives of the many people he met along the way.

Waters recounts his trek in his often uproarious and often touching new book, “Carsick” (Farrar, Straus and Giroux; $26). While other directors could choose to spend their late 60s sunning themselves by a pool in Los Angeles, Waters, for kicks, challenged himself to an adventure: hitchhiking across the country from his native Baltimore to San Francisco. (He divides his time between homes in these cities and others in New York and Provincetown, Mass.)

Waters talked about his latest book — and his passion for reading — at San Francisco’s Green Arcade bookstore, which hosted a reading for him. His answers have been edited for length.

Q: What’s happened to hitchhiking? Why don’t people do it anymore?

A: I’m hoping to bring it back because there is no such thing almost. I think it’s a green idea. It is an adventuresome idea. And it is fun to do it, it is liberating to do it because you don’t know what’s going to happen.

Q: How long do you think it would have taken you to cross the country if your name were John Smith?

A: Not that different because I would say maybe half the people who picked me up did not know who I was, or vaguely heard of me if I told them I made “Hairspray” or something. But they weren’t impressed. A lot didn’t know — they picked me up because they felt bad for me. They thought I was a homeless man down on my luck.

Q: You seem refreshingly indifferent to what people drive. What kind of car do you own?

A: I have no interest in cars. I have a plain, used Buick. I could run over 10 people, and you wouldn’t be able to describe my car. I’ve bought the same used car from the same man since I was 16 – a Buick every time. They always work, I don’t care what color it is. I don’t want people to recognize my car in case I want to commit a crime.

Q: In one of the novellas in the book — titled “The Best That Could Happen” — you imagine yourself displayed in a carnival as “The Man With No Tattoos.” Are you saying you didn’t get a tattoo to commemorate your journey?

A: No, I never had any desire to get a tattoo. If I was ever going to get one, I would get a plain anchor with a rope around it, the most unimaginative possible tattoo, like Popeye had.

Q: In the other novella, “The Worst That Could Happen,” you envision yourself in hell, where you watch “It’s a Wonderful Life” for eternity. On the flip side, what movie could you watch over and over again?

A: “Boom!” with Elizabeth Taylor and Richard Burton, directed by Joseph Losey. I have watched it for eternity. Right now, it’s still in my head, playing.

Q: Will your next book be about hitchhiking across the country in the other direction?

A: No! Definitely not. Somebody said, “Are you going to do a sequel?” What, in a Town Car? That would be kind of a pitiful followup, to go across the country with a driver. I tell you, the only thing terrible I did, when I used to live here, worse than hitchhike, we would take cabs and run. I was with my friend, and we used to do that when I was in my 30s. And a guy almost caught us and beat the s— out of us. And it really cured me of doing that. We did it daily. It was terrible. You know, this was in steal-the-book years, the liberation of ripping off “the man,” and all that bulls–.

Q: Did you get to read any books on your trip?

A: I didn’t read one thing. And you know, I always do read every night. I would be so exhausted that I just went to sleep to block it out.

Q: If you had to pack your bags today to cross the country, what books would you bring with you?

A: I would take a long book. I would take the one I’m reading now. I’m on Volume 2 of the Norway guy [Karl Ove Knausgaard] — “My Struggle.” But that’s heavy – you want to take a lightweight paperback, because weight is the thing. You don’t want to be running to get into a car with a bunch of bags.

Q: How many books do you think you own?

A: I don’t know, maybe 9,000 – a lot.

Q: How do you organize them?

A: Well, in my living room in Baltimore is some of my best fiction and art. I have true crime, I have all movie stuff in one place. It’s organized – I know where stuff is. But I have nothing in the bathroom. If you go in someone’s house and there is a basket of magazines next to the toilet, that is so disgusting.

Q: Where do you do most of your reading?

A: In bed, or on a plane.

Q: What are you reading these days?

A: I’m reading Lydia Davis, who I really love. I love this Italian woman, Elena Ferrante. I like “White Girls” [by Hilton Als].

A: What are you not reading these days?

Q: Whatever the stack of books that I have with me. I’ve been trying to read this biography of John Fowles — I always liked him because he’s so unpleasant.

Q: Do you have any favorite Bay Area bookstores?

A: Well, I obviously like this one [the Green Arcade], because I chose to do the signing here. I like City Lights. And my favorite of all is KAYO Books. It’s the best place to buy a present in the world. It’s the most amazingly curated bookshop, I think. But Bolerium Books is amazing, too, because they specialize in communist revolution and gay people (laughs). It’s such an odd mix.

Q: What does the Pope of Trash think about the new pope?

A: I’m sorry, I don’t trust him. I even trust him less because I think he’s given us lip service and not changing one thing. I went to the Vatican once – it was a bad idea. I went into the bookshop and I bought hideous, pious postcards and then I asked for a receipt, and the nun said, “We don’t give receipts at the Vatican.” Which threw me into a rage of like, “I guess not, so you can take this money and funnel it into anti-homosexual groups!” People had to drag me out of there. It’s not good for me to go into the Vatican.

JOHN McMURTRIE is the book editor of the San Francisco Chronicle. He is on Twitter @McMurtrieSF.