Washington’s robust economy, which added nearly 90,000 jobs last year, is proof that even with the country’s highest minimum wage, “this is a great place to do business,” Mr. Brunell said.

During a recession five years ago, the same group had argued that Washington’s high minimum wage law would send businesses fleeing to Idaho. The group sent out a news release with a criticism of the law from John Fazzari, who owns a family-run pizza business in Clarkston, Wash., just minutes from the Idaho town of Lewiston.

But now Mr. Fazzari says business has never been better, and he has no desire to move to Idaho.

“To tell you the truth, my business is fantastic,” he said in an interview. “I’ve never done as much business in my life.”

Image Jose Caro waits tables at La Cabana Mexican Restaurant in Post Falls, Idaho, a state with one of the lowest minimum wages in the country. His $5.75 base wage is 60 cents more than the Idaho minimum. Credit... Jeff T. Green for The New York Times

Mr. Fazzari employs 42 people at his pizza parlor. New workers make the Washington minimum, $7.93 an hour, but veteran employees make more. To compensate for the required annual increase in the minimum wage, Mr. Fazzari said he raises prices slightly. But he said most customers barely notice.

He sells more pizza, he said, because he has a better product, and because his customers are loyal.

“If you look 10 years down the road, we will probably have no minimum wage jobs on this side of the border, and lots of higher-income jobs,” Mr. Fazzari said.

Job figures from both states tend to support his point. While Idaho leads the nation in new job growth, it has a far higher percentage of minimum-wage jobs than Washington. Minimum-wage positions make up just 2.4 percent of the jobs in Washington, while about 13 percent of the jobs in Idaho pay at or less than the proposed federal minimum wage, according to a study done for the state last year.