Meanwhile, Russia’s state-owned Rosatom dominates the nuclear export industry, actively building the first atomic power plants in newcomer countries such as Turkey, Egypt, and Bangladesh. On Monday, the Kremlin announced its latest deal to build Vietnam’s debut nuclear plant. And China is building nearly as many reactors at home as the rest of the world combined, at a relatively rapid clip.

States started banning new nuclear power plants even before the partial meltdown in 1979 at the Three Mile Island nuclear plant in eastern Pennsylvania. The Atomic Energy Commission, the federal regulator in charge of both overseeing commercial reactors and promoting the industry, was increasingly seen as too cozy with the companies under its authority. An anti-war movement with limited options to slow the military’s atomic weapons race instead trained its attention on the civilian power industry, and environmentalists took issue with the relatively small but extremely long-lived volumes of radioactive waste that nuclear plants produce.

California enacted one of the nation’s first major statewide bans on building new nuclear plants in 1976, three years before Three Mile Island. Until then, states and municipalities had only minimal restrictions on nuclear power plants, which fell primarily under federal jurisdiction. But a 1974 law in California reorganized the Golden State’s bureaucracy, centralizing energy regulation for the first time in Sacramento and granting the newly established California Energy Commission powers to restrict permits for atomic energy facilities until a plan to permanently deal with nuclear waste came to fruition. Through its top cultural export, the state broadcast its skepticism of atomic energy: Released just 12 days before the Three Mile Island accident, a Hollywood thriller starring Jane Fonda, ​“The China Syndrome,” depicts a dangerous cover-up of a problem at a nuclear power plant.

In the years that followed, more states, including Maine and Oregon, adopted California-inspired moratoria predicated on a permanent solution for nuclear waste coming into commercial use, according to data from the National Conference of State Legislatures. Others — including Hawaii, Massachusetts, Rhode Island, and Vermont — effectively banned nuclear construction by making any new reactors subject to politically unattainable approval by the state legislature. A handful of states also rewrote rules to require a statewide referendum on building a new nuclear plant.

Some states enacted only partial bans. New York, for example, just barred construction of nuclear reactors on Long Island, where protesters blocked the Shoreham Nuclear Power Plant from coming online and financially crippled the region’s utility, forcing a state takeover.

Attitudes toward nuclear power have since evolved. Despite a drop in support following the meltdown at the Fukushima-Daiichi nuclear plant in northern Japan in 2011, a majority of Americans in both political parties have come to favor an expansion of nuclear energy. Polls from the Pew Research Center and Gallup show the highest support in years.

In 2016, Wisconsin became the first state to reverse course. Lawmakers in the factory-dense state pitched legislation to repeal the ban as a way to shore up the supply of reliable, clean power for manufacturers whose shareholders increasingly demanded a lower carbon footprint.

Seeking an alternative to fossil fuels that could make use of existing transmission lines and boilers at coal-fired plants, Kentucky followed suit a year later. Montana came next, in 2021, then West Virginia in 2022.

Illinois, by far the largest user of atomic energy of any state, only partially lifted its ban at the end of 2023, legalizing construction of as-yet-unbuilt small modular reactors with an output of 300 megawatts or less. While more than a dozen developers are racing to commercialize various kinds of so-called SMR designs, the promise of cheaply mass-producing identical reactors remains mostly theoretical. The only modern nuclear reactor design in operation in the U.S., the 1,100-megawatt Westinghouse AP1000, remained effectively banned in Illinois until January, when Democrat Gov. JB Pritzker fully repealed the moratorium and called for new plants.

The changing sentiment is a necessary but not sufficient precondition for more nuclear plants to start construction in the U.S. Big questions remain about how to finance projects, train workers, and establish supply chains for novel kinds of reactors.

Alexander C. Kaufman is a contributing reporter at Canary Media, and an award-winning writer who has covered energy and climate change for more than a decade.