The vote does not mean there will be a strike, but it is an important first step.
Many teachers said they were excited to vote "yes" and take the future into their own hands.
"I hope this with give some leverage to us, and hopefully, we'll get what we want," said teacher Natalie Ramirez.
"It's a fundamental issue of fairness. You're asking people to work 20 percent more time for 2 percent more money. That's an 18 percent paycut. That violates everything fair labor says," said Mark Lipscomb, also a teacher.
Teacher's union President Karen Lewis cast her "yes" vote at King College Prep on the South Side Wednesday. She said she was confident the union will get the required 75 percent of the rank and file to pass the strike authorization.
"I think it sort of now makes them understand they have talk to us about the issues that are important to us," said Lewis.
Chicago Public Schools CEO Jean-Claude Brizard is calling Wednesday's vote premature, especially since an independent panel has yet to release its findings on the contract issues separating the two sides.
"We have always taken teachers seriously and are serious about coming to a resolution and having a contract that is fair to the teachers and the taxpayers," Brizard said.
The teachers' contract expires at the end of June.
A strike authorization vote does not necessarily mean the city will see a repeat of 1987 -- the last time the CTU hit the picket line. It does signal an increasingly confrontational relationship between the CTU and CPS and city hall.
Teachers are responsible for counting the ballots but to ensure the integrity of the vote they have asked an outside organization - Arise Chicago, an interfaith religion labor coalition - to witness the official count. The group's members say they want the final result to be respected and upheld by the union, as well as the city and school district.
"We believe it's important that the public be assured that this vote has been well conducted, openly conducted and fairly conducted," said Rev. John Thomas, Arise Chicago.
Some parents can't help being little worried.
"I was in school when they had strikes as well and it hurts the students...the students actually lose," parent Dennis Shaw told ABC7 Chicago.
"We're not talk about strike. We're trying to get a contract. People need to understand that, and this vote will help us get a contract," Lewis said Tuesday.
"We're taking negotiations very seriously, so to ask and say I need that --to do something else -- I think is unfair," said Brizard.
For Wednesday's strike vote to pass, the teachers union needs 75 percent of its 25,000 teachers to vote for it. The results are expected to be announced Friday.