For the fourth year in a row, Portland, Ore., has been named the most sustainable of the 50 largest U.S. cities. The rankings by green org SustainLane, which take 16 economic and quality-of-life factors into consideration, “reveal which cities are increasingly self-sufficient, prepared for the unexpected, and taking steps toward preserving and enhancing their quality of life,” says the group. After Portland, this year’s top 10 include San Francisco, Seattle, Chicago, New York, Boston, Minneapolis, Philadelphia, Oakland, and Baltimore. The bottom 10: Nashville, Arlington (Tex.), Long Beach, Colorado Springs, Indianapolis, Virginia Beach, Memphis, Las Vegas, Tulsa, Oklahoma City, and Mesa. Columbus made the biggest improvement over SustainLane’s last list, jumping from No. 50 to No. 30; Las Vegas saw the biggest freefall, from No. 27 to No. 47. Unsurprisingly — but still unfortunately — the most affordable cities tended to score the worst on public transit, bike-friendliness, and walkability.