Though it doesn't explain all the data, IMO a big factor is the availability of public transportation, as Grits has argued in the past. The Atlantic nailed it: Some cities are built to encourage drunk driving, particularly here in Texas. As Eric Nicholson wrote at the Dallas Observer's Unfair Park
This should make intuitive sense to anyone who doesn't live in Uptown, Deep Ellum or Lower Greenville and has ever gone out for a few drinks. Assuming no one volunteered to be designated driver, you're basically left with two choices: pay an ungodly amount for a cab or drive drunk and hope for the best. In places like New York, where things are denser and more accessible by foot or by public transportation, there are more viable options.Bingo! As Nicholson pointed out, "That's not to say that people in Dallas have an excuse to drive drunk, just that the data make sense." However, Grits would add that the data show urban planning and other public policy decisions play a big role in DWI death rates that the enforcement-only crowd generally fails to acknowledge. Grits doesn't believe there are fewer drunks in New York, Washington D.C., or Philadelphia than in Dallas, Houston, or Austin; I just think those cities' governments had the foresight to give people a way to get home without climbing behind the wheel of a car.