The Montgomery County Council voted overwhelmingly to establish the county’s own minimum wage Tuesday, approving a historic increase that will lift the hourly rate to $11.50 by 2017 — far above the current state and federal minimum of $7.25.

The council’s action, which followed nearly four hours of tense and occasionally acrimonious debate, is the leading edge of an unusual regional effort by Montgomery, Prince George’s County and the District to raise the wage. The Prince George’s County Council is expected to vote Wednesday, and an initial vote by the D.C. Council is set for Dec. 3.

It is also part of a national movement by state and local governments to address growing wage inequality where Congress has not. The federal minimum has not been raised in four years. New Jersey, California and New York have all approved minimum wage increases this year.

The Montgomery bill increases the wage in annual steps to $8.40 in October 2014, $9.55 in 2015, $10.75 in 2016 and $11.50 in 2017.

During debate, the measure was amended to extend the phase-in period from three to four years, reflecting concerns that the wage was being raised too high and too fast. At $11.50, an individual’s annual income is $23,600 — still well below what it takes to subsist in Montgomery, where living costs are significantly above the national average.

Council member Marc Elrich (D-At Large), the bill’s chief sponsor, said that it was not politically possible to do more at the moment and that he was satisfied.

“I’m very happy. It’s substantively what I wanted,” he said. “You can make a big difference to people.”

Two of his co-sponsors, Council President Nancy Navarro (D-Mid-County) and Valerie Ervin (D-Eastern County), expressed concern that the addition of the fourth year would damage the ­chances for regional action. But D.C. and Prince George’s leaders said Tuesday evening that plans remain intact.

“In 2016 or even 2017, it’s a victory for the region,” said D.C. Council Chairman Phil Mendelson (D), who made calls to Montgomery council members Tuesday in advance of the vote.

On Monday, a D.C. Council committee unanimously passed a measure to reach $11.50 by 2016, and a super­majority of council members said afterward that they would support the bill in the initial vote by the full council next week.

Prince George’s postponed action last week to wait for Montgomery’s vote. Council Chair Andrea Harrison (D-Springdale) said through a spokesman Tuesday that the council “will likely make changes to mirror Montgomery County, as long as it lessens the impact on retail businesses in Prince George’s County.”

Council member Eric Olson (D-College Park) said he was “confident” Wednesday’s vote would end in approval.

“The objective here is to improve the economic conditions of our lowest-paid workers, and this would improve the situation. Legislation sometimes is about compromises. It would still be a big step forward for our lowest-income workers,” he said.

Montgomery’s vote represents a significant legislative achievement for Elrich, a former elementary school math teacher who is regarded as the most liberal on the left-leaning, all-Democratic council. As such, he has often been the lone opposing vote on many issues.

He received a chilly reception when he first announced his intention to introduce minimum wage legislation in late August, shortly before Labor Day. Many Montgomery council members maintained that the wage was strictly a state and federal matter.

But Elrich persisted and said he developed the idea of a regional approach after speaking with business leaders who expressed concern that unilateral action by Montgomery could put the county at a competitive disadvantage. He said he reached out to Harrison at a meeting of the Maryland Association of Counties in the summer and later spoke to Mendelson.

Elrich’s cause also benefited from a national and regional political climate favorably disposed to raising the wage. National polls showed Americans overwhelmingly in favor of President Obama’s unsuccessful attempt to secure an increase.

The Montgomery council’s final 8 to 1 vote — Phil Andrews (D-Gaithersburg-Rockville) opposed the measure — papered over serious differ­ences and legal uncertainties surrounding the bill.

County attorneys told council members that the bill was limited to covering employees doing work in the county for firms “operating and doing business in the county.” Council attorney Robert Drummer said some situations — such as a landscaping company from outside the county sending workers into Montgomery — might be “problematic” from a legal standpoint and vulnerable to a court challenge.

Andrews and council member Craig Rice (D-Upcounty) unsuccessfully pressed for the council to wait for the Maryland General Assembly to act.

But others maintained that delay was not an option.

“Delaying the bill is killing the bill,” Ervin said. “Let’s have the courage to do the right thing.”

The turning point came when council member Roger Berliner (D-Potomac-Bethesda) proposed amending Elrich’s bill by raising the wage to $10.75 in 2016 and the lesser of $11.50 or $1 over the state minimum in 2017. Rice, who was expected to join Andrews, Nancy Floreen (D-At Large), Hans Riemer (D-At Large) and George L. Leventhal (D-At Large) on Berliner’s resolution, suddenly switched and agreed to back $11.50 over three years.

Berliner’s motion passed 5 to 4, but Rice’s defection effectively collapsed the coalition, setting the stage for an amendment by Elrich to raise the minimum to $11.50 over four years with no conditions attached.

His amendment passed 6 to 3, allowing the final vote to approve the wage increase.