From prioritizing green spaces to encouraging the use of electric vehicles and alternate fuel sources, the Mile High City does its part for the planet. Denver was ranked the No.15 most sustainable city in the U.S. in 2024 by Coworking Café, recognized for its large number of green buildings and eco-friendly coworking spaces. Denver ranked No. 1 on Architectural Digest's 2023 list of the “Top 50 Most Climate Resilient Cities” due to factors including fewer threats of extreme weather damage and city-level initiatives to support clean energy such as solar. Denver is the only U.S. city included on National Geographic’s list of “Eight Sustainable Destinations for 2021 and Beyond,” thanks in part to 125 miles of bike lanes and solar gardens planned throughout the city. Online insurance marketplace Policygenius echoed this sentiment in 2022, naming Denver as the tenth-best city to live in by 2050 for climate change. Denver’s climate and mindset are conducive to enjoying the great outdoors, whether hiking, biking, running or walking. In September 2025, Denver International Airport (DEN) was recognized as the No. 1 Green Fleet of 2025 by NAFA Fleet Management Association for its outstanding efforts in reducing environmental impacts and promoting sustainability within its fleet operations.