EDGEBROOK — When Mayor Rahm Emanuel announced last fall that Wildwood Elementary School would finally get an annex to relieve severe overcrowding, Holly Gutierrez was one of many parents who began to sob with joy and relief.

But on Tuesday, when Emanuel returned to the school Tuesday to break ground on the three-story, $15 million annex, Gutierrez was all smiles, hopping from one foot to the other with excitement as construction officially got underway.

"This is very emotional," said Gutierrez, who is president of the school's Parent-Teacher Association. "But it is all joy and excitement that this is really going to happen."

Heather Cherone was at the event, and she says it was a real "love fest" between Mayor Emanuel and Ald. Mary O'Connor:

Mayor Rahm Emanuel praised Wildwood parents for their "resilience and persistence," and recalled how many attended city and school meetings waving signs shaped like the letter "W" to lobby for an annex. View Full Caption DNAinfo/Heather Cherone

Wildwood Principal Mary Beth Cunat said the annex, which will include a new lunchroom/multipurpose room, 12 classrooms, a computer lab, library, art room and administrative offices, would allow the school — already ranked among the city's best — to keep "getting better and better."

Ald. Mary O'Connor (41st) said the annex would make it possible for the school's students to lead "exemplary" lives.

O'Connor thanked the parents and teachers who lobbied school and city officials for years to relieve the overcrowding that had students studying in hallways, the cafeteria and broom closets at the Edgebrook school.

O'Connor praised Emanuel for "rolling up his sleeves" and ending "decades of inaction and decades of lip service" by other city officials that forced students to study in classrooms bursting at the seams.

"This annex is a gigantic step forward," O'Connor said.

Emanuel returned O'Connor's compliment, calling her a "very strong advocate" for the Edgebrook community, and joking that there was nothing gentle about her repeated requests that he address overcrowding at Wildwood.

Both Emanuel and O'Connor are up for re-election.

Although though the main building was meant for 240 students, 424 students were enrolled at Wildwood during the 2013-14 school year. That gave the school a utilization rate of 177 percent, one of the highest in the city, according to CPS data.

Even with a four-classroom modular building, the school had an adjusted utilization rate of 128 percent, which is still considered overcrowded, according to data provided by CPS.

Forcing students to study in such cramped conditions limits their potential, Emanuel said.

"You can't do it when you are all sitting in the hallways," Emanuel said.

Schools throughout the Far Northwest Side are filled to overflowing with students because of an influx of families looking for affordable homes in a relatively safe area of the city, according to city and school data.

Emanuel began his remarks on Wildwood Park 's broiling-hot basketball courts — which will be removed to make way for the annex — by thanking the parents who lobbied him and the school board for their "resilience and persistence," and recalled how many attended city and school meetings waving signs shaped like the letter 'W.'

The annex, which is expected to be ready in September 2015, will double the size of the school at 6950 N. Hiawatha Ave.

Enrollment at the school, which offers a magnet program and an International Baccalaureate curriculum, is expected to grow for the next three to four years, district officials said.

The annex, which will be built on what is now Wildwood Park's basketball court and water play area, was criticized by members of Friends of the Parks for setting a bad precedent that open space can be removed for other needs.

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