DC Mayor Vince Gray's "Sustainable DC" plan came out earlier this week and I was pleasantly surprised to see that it contains something that often goes missing from urban sustainability plans—a clear call for growth, and the aspiration that the city will add 250,000 residents by 2030.
That's great to see, because while making DC greener is a great idea the fundamental thing mayors of traditional cities need to know is that they're already much greener than the average American suburb. In cities car trips are shorter, car trips are a shorter share of all trips, and attached houses are more energy efficient than detached single-family homes. When cities grow denser those benefits tend to get even bigger. Long story short, for a city like DC one of the greenest things it can do is just add people and it's good to see a sustainability plan that explicitly recognizes that.