DETROIT — Michigan voters on Tuesday made their state the first in the Midwest to legalize recreational marijuana, passing a ballot measure that will allow people 21 or older to buy and use the drug and putting conservative neighboring states on notice.

Three other states had marijuana-related measures on their ballots. North Dakota voters decided recreational pot wasn’t for them, while voters in Missouri passed one of three unrelated measures to legalize medical marijuana. Utah voters also were considering whether to allow medical marijuana and to join the 31 other states that have already done so.

Including Michigan, 10 states and the District of Columbia have legalized recreational marijuana. And Canada recently did so. But the passage in Michigan gives it a foothold in Middle America and could cause tension with neighboring Indiana and Ohio, which overwhelmingly rejected a 2015 legalization measure.

“Troopers that work along the state line are very cognizant of what’s going on up north,” said Indiana State Police Sgt. Ron Galaviz, a spokesman for the agency’s Fort Wayne Post, which stretches north to the Michigan line.

He said if the referendum passed, “we know some of our citizens are going to go over to Michigan to partake.” And those who return either under the influence or in possession of pot may learn the hard way that it remains illegal in Indiana.

“We’ll enforce our laws as written,” added Galaviz, a Michigan native. “If you’re traveling to or through our state, we really don’t want you bringing it down here.”

The Michigan law will take effect in about a month, as the election first has to be certified by the Board of State Canvassers. Ten days after that certification, people age 21 or older will be allowed to have, use and grow the drug, but the process of establishing regulations for its retail sale could take about two years.