Dr. Matsusaka said much of the dissatisfaction that has led to more citizens’ initiatives during the past two years may have been caused by an increase in the number of states where the legislatures and governors’ offices are controlled by the same political party. Some of the most heated battles have occurred in Democratic-controlled California, and Republican-dominated states including South Dakota, which has not elected a Democratic governor since 1974.

“When one party dominates, our elected representatives think they can do a lot of things with impunity, as long as they cater to their base,” Dr. Matsusaka said. “People feel like, ‘I know this issue. Why can’t I make these decisions?’”

Lawmakers point out, though, that many ballot initiatives are driven not by ordinary residents but by special interest groups, often from somewhere else. In many cases, the organizations have a stake in the outcome, and are willing to bankroll the costs of paying petition drive companies to collect signatures and then advertising statewide to build support. Some initiatives in California have cost more than $100 million.

With Republicans gaining dominance in more state capitals in recent years, many of the nation’s recent ballot initiatives have originated with left-leaning organizations that are frustrated with the lack of legislative action on matters like recreational marijuana and conditions for farm animals.

Over the decades, though, conservative groups have also been successful in pressing their agendas with referendums — including Proposition 13 in 1978, which capped California property taxes and helped spark a nationwide movement of public resistance to tax increases; and what are known as Three Strikes laws, beginning in Washington State in 1993, which mandated long prison terms for repeat offenders.

In South Dakota, which began allowing ordinary citizens to propose ballot initiatives in 1889, voters will get another chance in November to pass an ethics measure. The initial referendum — which limited lobbyists’ gifts to politicians, required more frequent reporting of campaign contributions, and established public financing for campaigns — was approved by 52 percent of voters in 2016, before lawmakers repealed it.