Runners arrive for Chicago Marathon Sunday

CHICAGO (WLS) -- Runners from around the world have begun to arrive in Chicago for the Bank of America Chicago Marathon Sunday, Oct. 9.

Chuck Aron got in a short run Thursday in preparation for a much longer one Sunday. The 26.2 mile marathon will be the culmination of six months of racing for Aron. In fact, the Chicago Marathon will be his 73rd race since May, all in honor of his brother-in-law who died of Alzheimer's disease.

"Seventy-two down, one to go," Aron said.

The 73 races are because he turned 70 this year and his brother-in-law-would have been 73. Aron has raised tens of thousands of dollars for the Alzheimer's Association over the last decade. He is one of thousands of runners who run the Chicago Marathon for charity. In fact, runners raised nearly $19 million for various charities during 2015's race, making it the biggest charity event in the state.

"Chuck is an example of the philanthropic aspect of the event," said Carey Pinkowski, Bank of America Chicago Marathon.

Another organization that benefits is Chicago Run, which coaches Chicago Public Schools students.

"We have about 65 runners that will be out there Sunday running the race for us and raising about $100,000 on behalf of our kids," said Alicia Gonzalez, Chicago Run.

The race is also a boost for the economy. Organizers said it provides Chicago with an economic impact of more than $250 million for the weekend. It's also big business for sponsors like Nike. Marathon week is the busiest week of the year for selling running equipment. Nike also offers coaching.

"There's a high success rate of finishers at Chicago, so it's a really popular draw for that," said Nike running coach Emily Hutchins.

Every marathoner has a personal reason for doing the race. For Aron, it keeps him going when the going gets tough.

"It plays a major role in motivating. I also have requests from people who've donated, if I would wear a ribbon in memory of their loved one," he said.

Security along the marathon route will be tight, especially around the finish line in Grant Park. More restrictions than usual are expected because President Obama will also be in town during the marathon.