The group included 21 Chicago Fire Department firefighters, paramedics, EMTs and engineers, as well as Ald. Ariel Reboyras (30th Ward), who represented Mayor Rahm Emanuel.
The volunteers were greeted with applause and cheers Saturday night at O'Hare International Airport.
While on the island, they started their days before dawn and visited 54 towns. In addition to supplies, they also provided basic medical attention and cleared trees and other debris from roadways.
"If this area of Puerto Rico was poor before, they're devastated now," said District Chief Juan Hernandez.
They CFD personnel worked alongside Puerto Rican firefighters in areas where bridges were washed out and roads gone or near impassable. They helped carry medicine, water and food to remote areas.
"I had a little three year old and we gave them food, and she turns to her mother and says, 'Look, mom, we have food to eat.' I had to turn around and walk away from there because otherwise I would have started bawling," said Cmdr. Frank Velez.
"The devastation that people have seen they just haven't seen anyone up there in some of these rural areas in weeks. And we were the first faces they were seeing," said Cmdr. Richard Rosado.
Most of the CFD volunteers had family and friends on the island. Some tried to make contact, but their work meant they had only a few minutes with loved ones, including Cmdr. Rosado's father.
"He understood that I might be able to say goodbye to him so that was the hardest thing for me," Rosado said.
Some of the volunteers had military backgrounds but even with all their experiences, there was perilous moments.
"We were going up these mountains and the barriers that would prevent you from falling off are no longer there," said firefighter Robert Simpson. "The roads would cave in. I've never been afraid of heights before, but this really scared me sometimes."
"It was very treacherous," said Cmdr. Curtis Hudson. "I was this close to cutting our mission short."
The CFD volunteers completed dozens of missions. Now that they were home, they are grateful, tired and wondering about those they could not reach.
"There's a lot more that needs to be done, but we were only 22 of us and I believe we did impact thousands of people," Velez said.
Puerto Rico was ravaged by Hurricane Maria and Hurricane Irma last month, leaving dozens dead and infrastructure in shambles. Hundreds of evacuees from the island have been welcomed in Chicago since the devastating storms, according to the mayor's office.
"THIS IS A DISASTER"
This weekend, Rev. Jesse Jackson accompanied 150,000-pounds of supplies to Puerto Rico, which were delivered via a dedicated FedEx flight. The supplies, which included water, non-perishable food, hygiene items and schools supplies, came from Jackson's Rainbow PUSH Coalition and Chicago area Puerto Rican organizations.
"(The hurricane) lifted off roofs and tore out foundations," Jackson said via telephone. "A lot of people may be dead because we can't get to them yet. This is a disaster."