Corporations and municipalities are taking steps to help curb their carbon footprint. From Starbucks eliminating plastic straw usage, to an increase in eco-friendly commercial and residential real estate, being environmentally conscious has evolved into a movement in the public and private sectors.

Earlier this week, Commercial Café released a report on America’s most environmentally sustainable cities. While the cities on the list may not be a surprise, what these cities are doing to minimize their environmental impact just might be.

The report takes into account the proportion of energy a city uses from green energy sources, determining a city’s carbon emissions from transportation habits, as well as how eco-friendly city building codes are progressing and have progressed. San Francisco topped the list, and three of the top five cities are located in California.

The success of the Bay Area is due in part to a city initiative titled ‘Sustainable City’ that includes almost every aspect of city planning in an effort to go green. The plan has led to the creation of programs like SF Plant Finder which helps gardeners and ecologists interested in “greening up” city sidewalks and public land.

Other elements of Sustainable City include plans through the ‘SF Eco-District Program’ that help neighborhood districts like Chinatown become more sustainable through green public housing, update districts with green infrastructure, and engage community stakeholders to improve communities at an even larger scale. The most impactful environmental measure that San Francisco passed, however, has to do with solar energy. On Jan. 1, 2017, the city became the first in the United States to mandate solar and living roofs on most new construction.

With 30 percent of the city’s land area occupied by rooftops, this measure is not only a large reason why it leads the country in environmental sustainability, but also provides a blueprint for other cities to follow.

As sustainable practices are refined, and the cost of implementation lessens, more states are likely to reduce their carbon footprints and turn to sustainable practices. Those cities will turn to places like San Francisco to teach them how to accomplish it.