Teachers in Seattle public schools suspended a nearly weeklong strike on Tuesday, announcing that they had agreed on a new contract with the city’s school board. Classes are to resume on Thursday.

The strike began last Wednesday and delayed the start of the school year for 53,000 students and 5,000 teachers and support workers.

The agreement came after an all-night negotiating session, much of which was spent in a conference room in the school district’s central office. As union and district officials emerged at sunrise to announce the deal, they were congratulated by picketing educators who had been outside since 5 a.m., said Rich Wood, a spokesman for the teachers’ union.

Stacy Howard, a spokeswoman for the Seattle school district, called the move “a huge step.”

“What we’re going to do is focus on getting back and healing,” Ms. Howard said. “We’re all here for these kids.”

The union, the Seattle Education Association, announced the strike after complaining that members had gone six years without a cost-of-living wage increase and five years without increased funding for health care, among other issues.

The contract was approved by representatives from the union. The strike will formally end if union members vote to approve the contract. A vote was expected within three days, Mr. Wood said.

During the strike, educators picketed outside schools; students with working parents spent their days in community centers.

This was the district’s first systemwide strike since 1985, and the first major school strike since Chicago’s in 2012. It came at a time of great stress for the state’s education system. In 2012, the State Supreme Court ruled that Washington was not meeting its constitutional duty to adequately fund public schools. In August, the court imposed a fine on the state — $100,000 a day — for failing to address the problem.

Ms. Howard attributed teacher grievances to the state’s failure to remedy the situation. “This is what happens when education is not funded,” she said. “We want our teachers to have what they deserve, but we have to be fiscally sound. And it’s hard to do it.”