Sheerin first became a crossing guard 22 years ago. A few years down the road, she roped in her older sister, Sharon Matlack.
"I was working in a Catholic school, like helping out," said Matlack. "And she came to the school one day with the application and she stood there and filled it out for me and then she sent it in."
Both sisters crossed paths on Bingham Street, where they worked block-by-block for the past 15 years.
"We have busy lives and so we don't always get to see each other," said Sheerin. "But since we've been crossing guards, you know... we get to see each other every day."
Many students and parents gave well-wishes, gifts, hand-written cards, and of course, hugs, to the sisters on their last day of work.
"Some people believe in superheroes but I believe good people like Miss Mary," said Aaron Bashir from Northeast Philadelphia. "They are the superheroes because they are protecting our kids every single day."
Many students were sad to see the sisters go.
"Sometimes, when you have a bad day, she always has this nice smile on her face and it just brightens it up," said Cedar Grove Christian Academy student Brooklyn Tucker.
Despite hanging up the bright yellow vests, the crossing guard sisters won't be hitting the breaks on their friendship.
"We still will be able to do things together," said Matlack. "I wouldn't want to go through my life without her."
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