SEATTLE — The Seattle City Council passed an ordinance Monday that gradually increases the minimum wage in the city to $15, which would make it the highest in the nation.
The issue has dominated politics in the liberal municipality for months. Mayor Ed Murray, who was elected last year, had promised in his campaign to raise the minimum wage to $15 an hour. A newly elected socialist City Council member had pushed the idea as well.
The measure would start taking effect April 1, 2015.
The plan includes a phase-in of the wage increase over several years, with a slower process for small businesses. The plan gives businesses with more than 500 employees nationally at least three years to phase in the increase.
Those providing health insurance will have four years to complete the move. Smaller organizations will be given seven years.
The ordinance came from recommendations made by an advisory group of labor, business, and nonprofit representatives convened by Murray. After more than four months of discussion, the group presented its plan last month. Last week the council delayed implementation by a few months and approved a sub-minimum wage for teenagers, a provision opposed by labor representatives.
Although some local businesses have supported the measure, a group of restaurant owners oppose it, saying it would force them to scuttle expansion plans, decrease hiring, and possibly cut service hours.
Nick Musser, executive chef and general manager of the Icon Grill in downtown Seattle, doesn’t think the wage credit for tips should phase out after seven years and finds the differentiation between large and big companies irrelevant.
‘‘The reality is that the larger companies are going to ratchet up their wages and we’re going to have to play at that level anyway,’’ said Musser, whose restaurant employs between 50 and 60 people, depending on the time of year. Most of them are paid minimum wage.
San Francisco currently has the nation’s highest hourly minimum wage at $10.74. The current minimum wage in Washington state is $9.32 an hour.
Several cities and states have moved to increase their minimum wages in response to inaction from Congress on the federal minimum.
Earlier this year Minnesota raised the state’s guaranteed wage by more than $3, to $9.50, by 2016. California, Connecticut, and Maryland also have passed laws increasing their respective wages to $10 or more in coming years.
In Massachusetts, state senators this spring passed a bill to raise the minimum from $8 to $11 over three years; a version passed by their House colleagues would boost it to $10.50 over two years. The chambers need to forge a compromise before the bill heads to Governor Deval Patrick.
In New York, Democrats in the state Senate are redoubling efforts to raise the state minimum wage from $8 to $10.10 an hour and let high-cost areas including New York City raise it higher still.
Backers of the bill said Monday they are counting on support from Democratic Governor Andrew Cuomo to help boost support for the measure. The proposal includes automatic wage increases tied to inflation and empowers local governments to set minimums up to 30 percent higher than the statewide figure.
Cuomo had criticized the idea of local minimum wages but on Saturday said he would back the proposal.