Ten years of effort finally paid off for Las Vegas this week when officials announced the city government will now be powered entirely by renewable energy. After a large solar array, Boulder Solar 1, came online on Dec. 12, the city was able to buy enough carbon-free electricity to power its 140 buildings, streetlights and other facilities. The power flows from a mix of solar panels and hydroelectric turbines including the Hoover Dam. The renewables, plus energy efficiency savings, are estimated to save the city roughly $5 million per year, reports the Las Vegas Review-Journal.

Las Vegas is one of many cities pushing ahead with aggressive efforts to leave fossil fuels behind. The Vegas city council, after threatening to leave the grid entirely in 2015, struck a deal with NV Energy that would help the city get to 100% renewable. Casinos—including Wynn Las Vegas, MGM Resorts International and Las Vegas Sands Corp.—are now doing the same by installing acres of solar panels on their roofs, reports the Review-Journal.

Las Vegas city councilman Bob Beers said the switch to renewables, financed in part with federal dollars, is a taste of the future for municipalities. “As [power generation[ becomes decentralized, there will come a day when we won’t need the grid,” he said in Nov. 2015.

Las Vegas is on the vanguard as momentum behind climate action shifts from the federal government to cities in anticipation of new policies under a Trump Administration. In an open letter by the mayors of 48 major American cities including Los Angeles, New York, Chicago, and Phoenix to president-elect Donald Trump, they vowed “to forge ahead even in the absence of federal support,” noting that on Nov. 8 2016, Americans across the country approved more than $200 billion in measures funded by local tax dollars to reduce carbon emissions and other environmental pollution. ”The cost of prevention pales in comparison to cost of inaction, in terms of dollars, property, and human life,” the mayors wrote.

Eliminating all energy sector emissions in major cities will take decades—New York (pdf) and San Francisco (pdf) are both hoping to lower greenhouse gas emissions from 1990 baseline levels by 80% by 2050—but a few have already achieved it. The first major US city to switch its entire energy supply—and not just the city government’s—to renewables was Burlington, Vermont (pop. 42,000), in 2014. The city now powers its homes and business with a small dam on the Winooski River, a wind farm, an airport solar panel array, and 24 train-cars worth of wood chips sustainably harvested and burned each day. As a result, the city hasn’t had to raise utility rates in eight years, reports Politico. In 2015, Aspen, Colorado (pop 6,658) achieved 100% renewable energy production (pdf) by relying on a mix of hydro, wind, and landfill gas energy.

Now, a slew of other cities, from coast to coast and north to south, are on track to do the same between 2020 and 2030, says ICLEI, a network of over 200 local governments working to mitigate climate change in the US.