Here's a quote from it:
CP: One of the things I've always been so impressed by is your ability to use space and render D.C. almost like a character. In reading the work of some of your peers, I'm struck by how important place is to the success of a book. How much of your D.C. is real and founded in the streets and how much is created in your mind?
GP: Of course the characters are fictional and they're sort of walking through this fictional world, but as far as the grid goes, it's all pretty much real. I go out and check stupid things like, Is there a T in that alley behind Otis Place NW? I have to go to the alley and make sure that there is. In the historical books like Hard Revolution, if a character is walking down the street in April '68 in a particular week of that month, and the movie theater marquee says Guess Who's Coming to Dinner or something, it was playing in that movie theater on that day. I can guarantee you that. I don't make shit like that up. Even where it's crippling. In other words, [in The Turnaround] when Alex walks into the diner for the first time when he's a kid and the James Brown song is playing, and it's June in the book — if that song was released not until September of that year, I don't put it in there. It wouldn't have been coming through the radio. It's a long-winded way of saying I'm trying to leave a record.
I can relate to Pelecanos's comment about historical novels. When I was writing Treason at Hanford, my characters walked past a movie theater and they went to see a movie. I made a point of doing some research and finding out what films were playing in the spring of 1944. It's a fun way of writing but, like Pelecanos says, it can be a pain...if you care about getting things correct.