CHICAGO (WLS) -- The spring running season is officially underway in Chicago.
"I was concerned about the weather, but is a beautiful day to start running season in Chicago," said Rita Cook with Bank of America.
Thousands of people trekked down the city streets for the Bank of America Shamrock Shuffle.
"It's the spirit everywhere. People on the side cheering you on with their signs. It was great, kept us going whole time," said Leah Evenhouse, a runner from Dyer, Indiana.
The 42nd annual race created quite a special environment of runners and supporters.
"You're seeing a lot of people decked out in green. I saw some painted green folks earlier. So, the vibe is positive today," said Chase Woodall, another runner.
It's a race that has created traditions for many, including the "Green Guys," decked out in green from head to toe for the 15th straight year.
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They said the paint takes about an hour to get on and doesn't come off for days.
"We're going to bring the energy," said John, a Green Guy. "It's just a really fun tradition."
The Shamrock Shuffle also raises nearly $100,000 for local charities and sets the tone for the rest of the running season after a long winter.
"It's really nice getting out back with the runners, and the running community, and getting out there to run some miles," said Edgar Guerra with the Phoenix Military Academy.
Marco Galvan is the executive director of Students Run Chicago, which helping to raise money for charities. Most of the six or seven students running on Sunday are from the Pilsen and Little Village areas, he said.
"It's great to see all the people out here being excited about the start of our running season," Galvan said. "We're super excited!"
Many people took on the challenge on Sunday for the first time, while others tried to top their time from last year.
"I got to my goal. Last year, I got over 40. This year, I did below that. So, I'm really proud of that," said Christian Kellio.
Runners wrapped up the Shamrock Shuffle here at the Buckingham Fountain. That's an 8K race, which is nearly 5 miles, and the special atmosphere there brought in runners from outside the city and the state to participate.
"Because of the environment. I mean, Indiana cornfields, we come out here to the big city," Evenhouse said.
Grant Park will be closed to all vehicle traffic from 6 a.m. until about 3 p.m.
DuSable Lake Shore Dr., Ida B. Wells Dr. and N. Michigan Ave. will remain open.