When Donald Trump won the presidency in 2016 and again in 2024, promising to make the federal government hostile to climate action, many climate advocates argued that state and local governments would take up the mantle of pushing clean energy forward. That is the thesis behind the America Is All In coalition, a network of cities and states that have vowed to uphold America’s “climate commitments … [i]n the absence of federal leadership.”

The unspoken caveat in those claims is that the states leading on climate policy are clustered in a handful of liberal regions, such as New England and the West Coast.

This story was originally published by Grist.

The Democratic Party’s historic performance in this week’s midterm elections could shift that geography. Democrats have secured control of both legislative chambers and the governor’s office — a “trifecta” — in Arizona, Pennsylvania, and Wisconsin, three states that have spent years or decades under Republican or divided rule and have trailed on clean energy support. All three are perennial presidential battlegrounds that Trump carried in both of his wins. Unified control matters for lawmaking, too: because bills in these states must pass both chambers and be signed by the governor, a trifecta can clear the divided-government bottlenecks that have stalled climate legislation there for years. Democrats also restored trifectas in Minnesota, Michigan, and Nevada this week, though the party last held unified control in those states earlier this decade.

“It is impossible to overstate how monumental these results are,” said David Weiskopf, senior policy director at Climate Cabinet, a nonprofit that works to elect climate-focused candidates and pass state climate policy. He noted that the six states with new Democratic trifectas would rank among the world’s largest emitters if they were a country, rivaling Canada and Saudi Arabia. “This is just a massive opportunity to make progress.”

Here is how the election results could open the floodgates for new climate policy in Wisconsin, Pennsylvania, and Arizona.

Wisconsin

Wisconsin has been far less ambitious than its Upper Midwest neighbors about moving its power sector off fossil fuels. While Michigan and Minnesota have both passed laws requiring all of their electricity to come from clean sources by 2040, Wisconsin set a modest 10 percent renewable electricity standard more than two decades ago. The state blew past that goal but never adopted a new target. Unlike most other states, it does not even require utilities to plan what kinds of power plants they intend to build, and it draws a larger share of its electricity from coal than its immediate neighbors.

Renewable energy advocates in the Badger State believe short-term gains are within reach now that Democrats hold their first trifecta since 2010. Erik Kanter, policy director of the nonprofit Clean Wisconsin, said he believes the new Legislature can agree on the “low-hanging fruit” of requiring utilities to plan for the future, which he said would nudge more of them to build renewables rather than extend the lifespans of gas and coal plants. The Legislature failed this year to pass a law that would require data centers to source their power from clean sources, and Kanter expects such a measure to pass once Democrats take control. Lawmakers are also likely to renew programs such as Knowles-Nelson, a longstanding fund for parks and ecosystem preservation that once enjoyed bipartisan approval but has lost Republican support in recent years.

Weiskopf believes even more ambitious moves are in the offing. He expects Wisconsin’s incoming legislators to pursue a 100 percent clean electricity standard, filling what he calls a “Wisconsin-sized hole” in the Upper Midwest. Such a standard would not only help phase out coal within the state; it would also make it easier for neighboring states to meet their climate goals, because the entire region shares one interconnected power grid.

Pennsylvania

Democrats have long known the Pennsylvania Senate as the place where climate policy goes to die. Even after the party flipped the lower chamber a few years ago, Republican leaders in the upper chamber often refused to bring climate bills to a vote. The Keystone State’s status as a large producer of both natural gas and coal has also made it difficult to build agreement within the Democratic Party on clean energy proposals.

“You don’t want to let yourself fully imagine what it can be, because you’ve been let down in the past,” said Lindsey Williams, a state senator who represents a swath of the Pittsburgh metro area. “Now we’re in that moment of, wow, there’s so many things that we can accomplish.”

Every year since 2019, Williams has introduced a bill that would establish mandatory energy and water efficiency standards for appliances such as ovens and showerheads, a measure she said could save consumers millions of dollars a year. The legislation has never moved forward, but she believes it will in next year’s session.

She hopes Democrats will use their first trifecta since 1993 to advance a full-scope climate agenda. In addition to bills that would allow community solar and warehouse rooftop solar, Democratic lawmakers want to pass a funding package for struggling mass transit systems such as Philadelphia’s. The $1.5 billion infusion would help prevent the transit “death spiral” facing those systems and reduce reliance on gasoline-powered cars.

The state’s reelected centrist governor, Josh Shapiro, appears to be on board with at least some of these proposals. Although he withdrew Pennsylvania from the Regional Greenhouse Gas Initiative, a Northeast-wide carbon pricing system, he has promised to create a similar cap-and-trade system for Pennsylvania itself if he can secure legislative support. He has also named mass transit funding as a leading item on his agenda for the new legislative session next year.

Democrats will nonetheless have to tread carefully: while they will control both chambers, they will hold slim majorities in each and may have only a narrow two-year window to pass climate policy before one flips back.

“We need to be brave and lead,” Williams said. “Yes, what are the low-hanging fruits, but what are the big ambitious things that we can get done this session?”

Arizona

Arizona’s new Democratic trifecta is the state’s first since 1966 — decades before the general public was even aware of global warming. The Grand Canyon State has ample sunshine and wind, its renewable energy industry has grown quickly in recent years, and its grid is cleaner than those in regions like the Midwest. Many of the newly built suburbs of the Phoenix metroplex also tend to be heated with electricity rather than natural gas.

Yet Republicans in the state Legislature have all but banned climate and environmental policy, prohibiting the state government from regulating greenhouse gas emissions or energy use, and numerous climate and water bills have failed in recent years.

Lauren Kuby, a longtime Democratic legislator who represents the Phoenix suburb of Tempe, said she and her colleagues have a long wish list spanning several issues. Their first order of business is to reform the Arizona Corporation Commission, the state’s utility regulator, which Kuby said has been slow to embrace technologies such as solar and wind even as developers seek to build more of them. Legislators want to pass a law directing the commission to make utilities invest in solar, batteries, and “virtual power plants” — networks of homes and businesses that coordinate their energy usage. As part of the reform, they might even change the commission’s name, dropping “corporation” in favor of “public utilities.” Two Democrats who appear set to win seats on the commission will make these reforms easier to push through.

The Legislature could also break long-standing logjams on the crucial issue of water — a scarce resource in a desert state where climate change is worsening droughts. Kuby and other senators have tried for years to pass a bill regulating groundwater pumping in the state’s rural areas, home to massive dairies and alfalfa farms such as Riverview and the Saudi-backed Fondomonte, which have been blamed for sinking land and dried-up residential wells. The bill has failed in several legislative sessions, but Kuby believes some form of regulation can pass in the coming year, bringing an end to the water free-for-all in the desert areas outside Phoenix.

“That has been languishing and has not been heard in the Legislature, even though we have agreement from a lot of Republicans on water and environmental protection,” Kuby said. Of the trifecta, she said, “It’s a game-changer.”

Grist is a nonprofit, independent media organization dedicated to reporting on climate change.