The Chicago Teachers Union’s 25,000 members voted overwhelmingly to ratify their contract, officially ending the 11-day strike that was suspended on Oct. 31, union officials announced Friday night.

The union said 81% of members voted yes with 80% of votes counted as of 10:15 p.m Friday. It is a five-year contract, making this the longest contract since 2012. After the last walkout in 2012, the contract was ratified with an 80% yes vote.

“This contract is a powerful advance for our city and our movement for real equity and educational justice for our school communities and the children we serve,” CTU President Jesse Sharkey said in a statement. “We live in one of the richest cities in the wealthiest nation in the world, and finally Chicago must start investing in the future of our city—our children.”

Labor expert Robert Bruno described the deal as a paradigm-shift because the school district commits to providing remedies for overcrowded classes and to hiring additional support staff, such as nurses and social workers. These gains are significant because the school district isn’t required to negotiate over these topics and could have taken the union to court for striking over them.

Sharkey has said it’s not a perfect contract, but in a letter in the union’s magazine he said it “put something in place that makes your life at work better, and we have achieved that through tremendous effort and selflessness.”

He touted wins that will reduce workloads, limit class size, provide more resources for students learning English and protect services for special education students. The union also got commitments from the school district to hire a nurse and social worker for every school, as well as additional support staff for the neediest schools.

Teachers also will get a 16 percent raise over five years. Lower-wage workers, like office clerks and teacher assistants, will see even larger salary increases.

In his letter, Sharkey said contract ratification is only the first step.

“Collective bargaining agreements are only as strong as the workers who hold the bosses accountable and enforce their contract rights at every turn,” he said. These wins “are just words on a page without the vigilance of members to hold CPS and the mayor accountable for fulfilling their commitment to our schools.”

A $1.5 billion contract

Chicago Public Schools has said commitments in the contract will increase the school district’s budget by $558 million by the time it expires in June 2024. Altogether, the school district has said it will cost $1.5 billion over five years. During that same time, the district expects to take in well over $30 billion in revenues.

District officials say it will likely be able to cover all the costs in the contract with more than $100 million that it expects from increased property taxes each year. Some skeptics note a downturn in the economy would affect the amount of property taxes the school district could bring in.

But district officials also say it is expecting the state to provide between $60 to $70 million more each year.

Also, according to the school district, its cost projections include $50 million of normal pension costs that will be fully covered by the state.

Chicago Mayor Lori Lightfoot argued that the contract is affordable and said she would have made many of the investments, such as hiring more support staff, even if they weren’t in the deal. She called the contract a historic deal for teachers.

Despite that, concerns have been raised about the district’s ability to finance the contract after this year. S&P Global Ratings last week said “the settlement has increased expenditures beyond anticipated revenue growth and without corrective measures, could potentially slow or reverse the board’s recent financial progress.” S&P noted, however, that the structural gap is “not insurmountable.”

Some “no” votes

Though the vote was overwhelmingly in support of the new contract, there was a fair amount of discord among members leading up to the vote

Bruno said the Chicago Teachers Union is particularly primed to have members vote against ratification because they are highly engaged. The fact that the CTU must reckon with a law that requires 75% of teachers to authorize a strike means it must spend a lot of time educating members about the issues, he said.

The strike itself also engendered strong opinions about the contract, he said.

“They really want to vote, they really see it as something important to do, and they feel really knowledgeable,” said Bruno, who is a labor relations professor at the University of Illinois at Urbana-Champaign.

When the tentative agreement came before union delegates last month, some 40 percent voted against it.

Some members were unhappy with the lack of details in the provision giving veteran teachers additional pay for experience. Currently, teachers get raises for each year of experience, called steps, until they reach year 14. To get a deal at the last minute, Mayor Lightfoot agreed to add $5 million for increases for teachers with more than 14 years of experience. How that will be doled out has yet to be established.

Also, some elementary school teachers were deeply disappointed the union did not win more prep time during the school day. When former Mayor Rahm Emanuel lengthened the school day, they say they lost time at the beginning of the day where they could grade papers and reach out to parents.

When the issue of prep time was brought up at rallies during the strike, it invariably drew loud applause. But the school district held the line, saying that offering more prep time would mean shortening the school day, which it was unwilling to do.

Other members were unhappy the union agreed to a five-year contract, when all along the demand was three years. And they were furious Lightfoot would only agree to makeup five of 11 missed school days, meaning teachers would lose pay for six days.

But ultimately many teachers said they were satisfied with the contract.

One teacher on Facebook listed the many things she was proud of in the agreement, including increased pay for low-wage school staff, that teachers could bank 244 sick days — not to be paid out, but pensionable — and that counselors would no longer be pulled away to do non-counseling tasks.

Sarah Karp covers education for WBEZ. Follow her on Twitter at @WBEZeducation and @sskedreporter.