According to Laura Schweigman, assistant to The Wire executive producer/writer/creator David Simon, all casting for the show is done locally through Pat Moran and Associates. Schweigman says all speaking roles on The Wire are union, so you better get your Screen Actors Guild card.
To be an extra, though, you can send Moran a résumé and an 8-by-10 head shot (black and white is preferred) with your height, weight, and if you're under 18, age. Mail it to: Pat Moran and Associates, 3500 Boston St., Baltimore, MD 21224. Make sure to include your phone number so they can call you if they're interested. And don't bother whipping out your video camera. According to Moran's web site, the firm accepts "Video Demo Reels, but, in practice, seldom find them useful."
Regardless of what you send Moran's way, it may be a while before you hear back because shooting for season four of The Wire has long since wrapped up and season five won't start filming until 2007. So do Schweigman a favor and wait. "Just so my mailbox doesn't explode," she pleads.