Maine and Maryland made history Tuesday, becoming the first states in which voters legalized same-sex marriage.
In Washington and Colorado, voters adopted landmark measures of their own - becoming the first states to legalize recreational use of marijuana.
A bill allowing same-sex marriages in Maine passed in 2009, but opponents petitioned for a referendum on the issue and that year 53% of voters opposed it.
In Maryland a referendum had sought to overturn a law approving same-sex marriage passed earlier this year by the Legislature. A similar vote was underway in Washington state.
In Minnesota, voters were being asked whether the state's constitution should ban same-sex marriage, a step beyond the state's existing law against gay marriage.
Across the nation, voters in 38 states were deciding sweeping ballot initiatives on everything from same-sex marriage and recreational marijuana use to whether genetically engineered foods should be labeled.
Nationally, 32 states have voted to restrict marriage to heterosexual couples while while six others - New York, Connecticut, Iowa, Massachusetts, New Hampshire and Vermont - and the District of Columbia have legalized it either by legislation or a judicial ruling.
In addition to Washington and Colorado, the recreational use of marijuana was up for a vote in Oregon. Two others were considering allowing pot use for medical reasons.
The Washington measure that was adopted would allow adults to possess small amounts of marijuana and also allow its sale to be regulated and taxed. Estimates have showed pot taxes could bring in hundreds of millions of dollars a year, but the sales won't start until state officials make rules to govern the legal weed industry.
Together, the marijuana votes in the three states represented a pushback against the federal government, which backs the drug's prohibition.
Massachusetts residents approved a new law legalizing medical marijuana for people with cancer, hepatitis C, Parkinson's disease, Lou Gehrig's disease, glaucoma, HIV, AIDS, Crohn's disease, multiple sclerosis and other conditions. The state becomes the 18th to do so. Arkansas voters are considering a similar law.
In California, voters were deciding whether to repeal the state's death penalty and replace it with life in prison without the possibility of parole. If passed, the 726 inmates on death row in the state would have their sentences commuted to life in prison. If so, California would become one of only two states in which voters have repealed the death penalty. The other is Oregon. In the 17 states where capital punishment is outlawed, the change came through legislative action.
Big spending on food issue
California voters also were determining whether the state should become the first to require that foods made from genetically modified ingredients be labeled. The closely watched race sparked a backlash from agribusiness and chemical conglomerates, which spent at least $44 million in a bid to defeat Proposition 37.
School funding also was a major issue in California, with dueling propositions on the ballot. One, sponsored by Democratic Gov. Jerry Brown, could bring in up to $9 billion a year.
In San Francisco, voters decided whether to consider draining an 89-year-old reservoir in Yosemite National Park that provides water to 2.6 million people in order to restore the Hetch Hetchy Valley to its former natural state.
In a tight race, Maryland voters were considering whether to expand gambling to include table games such as blackjack and roulette at the state's three existing casinos and the addition of a new casino near the nation's capital, in Prince George's County. More than $90 million had been spent on the gambling initiative by opponents and supporters, an unprecedented amount in Maryland for a single campaign.
Tax limits at stake
In Florida, voters rejected a constitutional amendment limiting tax revenue growth to increases in population and inflation. The proposal was based on a similar provision in Colorado.
Idaho voted on whether to approve a major school overhaul that would include phasing out teacher tenure, implementing merit pay and limiting collective-bargaining rights for teachers' unions.
A vote in Massachusetts on whether terminally ill patients can legally get drugs from a physician to end their lives was too close to call early today. The issue had been hotly debated in the heavily Catholic state. Similar laws have passed in Oregon and Washington.
Thirty-four states prohibit assisted suicide outright, while Massachusetts and six others ban it through common law. Montana's Supreme Court ruled that state law doesn't prohibit doctors from helping patients die.
Fight over a bridge
Whether a new bridge between Detroit and Canada can be built was on the ballot in Michigan. Manuel Moroun, the billionaire owner of Detroit's Ambassador Bridge, spent more than $30 million on a constitutional amendment designed to thwart construction of a rival bridge.
The state also was considering a law requiring two-thirds legislative support for tax hikes.
In New Hampshire, voters decided whether to add a ban on a state income tax - a tax the state doesn't have - to their constitution.
A proposal to phase out the estate tax was on the ballot in Oregon. The tax starts at 10% for married couples with $2 million in non-farm assets.