What Todd Litman said over on Planetizen about a month ago: Welcome to our neighborhood: A Manifesto for Inclusivity.
Key concept: An “affordable” neighborhood isn’t just about housing cost as a share of your income. It’s really about housing plus transportation costs. You can afford to pay more for where you live if where you live lets you get around for less — by foot, bike, or transit.
And his response to the commenter is worth citing as well: “There are few better sustainability strategies, which help achieve economic, social and environmental goals together, than to ensure that every household can find an affordable house in an accessible, walkable neighborhood. Everybody wins!”