The contentious relationship between Chicago's teachers' union and its mayor continues to fuel the Windy City labor and education dispute, say out-of-state observers involved in similar past negotiations. If history is any indication, they add, it's likely that the teachers' strike there could have been avoided.

While the two sides in Chicago still fail to agree on the exact details under contention in the second week of strikes, the general issues are consistent with national trends in recent history -- including class sizes, salaries and benefits, length of the school day and, most notably, teacher evaluations. The unique difficulty facing Chicago over the last year and a half, say the observers, is the way both sides are approaching the negotiations, leading to prolonged debates and yielding a warning to other school districts and unions across the country.

Just last week, the Boston Teachers Union and the Boston City School Department finally came to an agreement after two and a half years of negotiations. The Boston dispute was fought mainly over instructor raises and evaluation practices.

BTU president Richard Stutman told The Huffington Post that Chicago Mayor Rahm Emanuel's personality made a strike there hard to avoid.

"If we in Boston had to deal with someone as provocative as Rahm Emanuel, we too might have been out on strike," Stutman said.

In 2000, negotiations in Philadelphia regarding an extension of the school day and pay raises finally broke down when then-Mayor John Street imposed a contract that the union couldn't stomach. Philadelphia Federation of Teachers President Ted Kirsch -- who is now the AFT president of Pennsylvania -- called for a strike on a Friday before resolving the issues by 5:30am Monday morning.

The situation in Philadelphia doesn't stray far from the battle now being fought in Chicago, Kirsch told The Huffington Post.

"From my perspective, I think it's the ego of the mayor," Kirsch said. "It's what we had, too … In these cases you think the public officials would be the compromisers, but it was clearly the mayor who injected himself very directly … If there's a lesson to learn for mayors, stay the hell out and let the professionals negotiate."

In Philadelphia, the dispute was resolved before students missed even an hour of instruction. Kirsch chalks the successful negotiations up to staying focused on the issues at hand.

"Over the years I had some contentious negotiations, but they were never, ever personal," Kirsch said. "In both [the 1980 and 1981 Philadelphia teachers' strike] cases, it was the mayor trying to force a contract settlement."

But that personal detachment might not be possible in Chicago, where Emanuel's mayoral campaign trumpeted a promise to overhaul Chicago's school system. Among Emanuel's most prized education reforms: expanding charter schools and increasing school accountability -- touchy issues for public school educators who say charters pull public resources away from their classrooms and current accountability metrics unfairly rate teachers and schools.

Emanuel's office did not respond to requests for comment.

In the summer of 2011, Chicago Teachers Union President Karen Lewis expressed the frustration among teachers over the way CPS officials and the state had conducted themselves. "People are very upset," she said. "People feel disrespected."

Emanuel aside, CTU's decision to take the proposed agreement back to union members may further complicate matters, said John Dunlap, a member of the Boston schools' negotiating team.

"A 26,000-member union has to have faith in their leadership," Dunlap, the City of Boston's chief of personnel and labor, told HuffPost. "Each party needs to believe that each side has the confidence of their side to deliver their approval … When someone who hasn't been involved in the process gets involved, they find something they don't like that is not even subject to the negotiation."

Nevertheless, Dunlap hopes that the delay while union members review the contract is "just a wrinkle." He sympathizes with the Chicago teachers, but is glad the Boston dispute is settled.

"When I look at Chicago, I don't think, 'What's wrong with those people,'" Dunlap said. "I just think, 'Oh, thank God that didn't happen here.'"

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  • Tennille Evans

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  • Mary Edmonds

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  • Chicago Teacher's Strike Enters Second Week

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  • Karen Lewis

    Karen Lewis, president of the Chicago Teachers Union addresses union menbers during a rally Saturday, Sept. 15, 2012, in Chicago. Lewis reminded that although there is a "framework" for an end to their strike, they still are on strike. (AP Photo/Sitthixay Ditthavong)

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  • Striking Chicago public school teachers and their supporters march down Michigan Avenue on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off the job on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Striking Chicago public school teachers and their supporters rally following a march down Michigan Avenue on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off the job on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Striking Chicago public school teachers and their supporters march down Michigan Avenue on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off the job on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Teachers picket outside the Chicago Public Schools headquarters on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off of their jobs on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Striking Chicago public school teachers and their supporters march down Michigan Avenue on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off the job on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Striking Chicago public school teachers and their supporters rally before a march down Michigan Avenue on September 13, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off the job on September 10 after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • Thousands of public school teachers and their supporters rally outside the Hyatt Regency Hotel to protest against Penny Pritzker, whom they accuse of benefiting from being a board member of both the Chicago Board of Education and Hyatt Hotels on Thursday, Sept. 13, 2012 in Chicago. (AP Photo/Sitthixay Ditthavong)

  • Children in strollers join thousands of public school teachers rallying outside the Hyatt Regency Hotel, protesting against Penny Pritzker, whom they accuse of benefiting from her position on the boards of both the Chicago Board of Education and Hyatt Hotels on Thursday, Sept. 13, 2012 in Chicago. (AP Photo/Sitthixay Ditthavong)

  • Two-year-old identical twins Colton and Lucas Jordan join thousands of public school teachers and their supporters as they march along Chicago's Michigan Avenue, protesting against Penny Pritzker, whom they accuse of benefiting from her position on the boards of both the Chicago Board of Education and Hyatt Hotels on Thursday, Sept. 13, 2012. (AP Photo/Sitthixay Ditthavong)

  • Thousands of public school teachers and their supporters rally outside the Hyatt Regency Hotel to protest against Penny Pritzker, whom they accuse of benefiting from her position on the boards of both the Chicago Board of Education and Hyatt Hotels on Thursday, Sept. 13, 2012 in Chicago. (AP Photo/Sitthixay Ditthavong)

  • Teachers and their supporters rally in downtown Chicago on day four of the strike Thursday, Sept. 13.

  • Teachers and their supporters rally in downtown Chicago on day four of the strike Thursday, Sept. 13.

  • Teachers and their supporters rally in downtown Chicago on day four of the strike Thursday, Sept. 13.

  • Teachers and their supporters rally in downtown Chicago on day four of the strike Thursday, Sept. 13.

  • A large group of public school teachers marches past John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)

  • A large group of public school teachers rally at John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)

  • A family waves at a large group of public school teachers as they march on streets surrounding John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)

  • Chicago public school student Natalia Segal joins the picket line outside of Marshall High School on September 12, 2012 in Chicago, Illinois. More than 26,000 teachers and support staff walked off of their jobs on Monday after the Chicago Teachers Union failed to reach an agreement with the city on compensation, benefits and job security. With about 350,000 students, the Chicago school district is the third largest in the United States. (Photo by Scott Olson/Getty Images)

  • A large group of public school teachers marches past John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)

  • A young boy in a cart is pulled along by his mother at the tail of a group of public school teachers marching on streets surrounding John Marshall Metropolitan High School on Wednesday, Sept. 12, 2012 in West Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)

  • Thousands of public school teachers rally for the second consecutive day outside the Chicago Board of Education district headquarters on Tuesday, Sept. 11, 2012 in Chicago. Teachers walked off the job Monday for the first time in 25 years over issues that include pay raises, classroom conditions, job security and teacher evaluations. (AP Photo/Sitthixay Ditthavong)