Chicago Police officers seemed to be posted at nearly every intersection downtown as the city heightened security measures.
It was the bombing during the Boston Marathon earlier this year that inspired Marcy Wrzesinski to stand outside her apartment building on Sunday to cheer on the runners as they passed mile four in the Old Town neighborhood.
"The Boston Marathon I think freaked people out," Wrzesinski said.
A 10-year resident of Chicago, Sunday was the first time Wrzesinski made it out to watch the race.
"I normally watch from my bedroom window," she said. "I didn't want to shy away from it this year. I wanted to come out and give my support. Go America."
Wrzesinski and her husband Chet said they had not noticed extra security measures this year, except that newspaper boxes in their neighborhood had disappeared.
Spectators who had gathered on Wells St. in Old Town said they were surprised that there were so few uniformed police offices around.
"It's good that you don't see the presence because that makes people uncomfortable," said Kelly Kane, 43, who was cheering runners on as they approached mile 11.
Some runners high-fived and shook hands with the few officers who were visible along the route, said Bill Deitrick, a Gold Coast resident.
"I told the officer, I said, 'This is the best of humanity,'" Deitrick said.
Kane, who has volunteered in the past at the finish line, said people would typically pack into that area as the race drew to a close. That's not allowed this year because race organizers made the finish line accessible only to ticket holders.
"It's a shame that they can't do that, but it totally makes sense," Kane said. "I can understand why (officials) don't want people down there."
Deitrick, who along with his wife Emily was watching the marathon for the first time, said it had never occurred to him to worry about safety.
"It's America, it's an open society," he said.
The couple came out on Sunday because they heard helicopters from their Gold Coast home and figured it was a nice day to take in the race.
"Chicago gave 'em a heck of a day for this," Deitrick said. "It's a perfect day."
A number of runners said the Boston bombings would not deter them from focusing on today's race. They were confident that the level of security here could prevent any terrorist attack.
One runner, Shannon Seiferth, 23, said the bombings crossed her mind only because today's marathon was such a large-scale event with thousands of people participating. But she was not worried.
"I think the security measures are in place and I think people are going to be on high alert," said Seiferth, of Chicago.
She's running the race with Emily Stewart, 23, of Chicago. The two were classmates at the University of Michigan. Both were running in their first marathon.
To pass the time of the lengthy race, the two compiled playlists on their music devices, including music from rapper Eminem.
At the corner of Jackson Boulevard and Halsted Street in Greek Town, Maxines Jones, 54, of Country Club Hills was waiting for about 15 friends to come running by. Jones said she had run the race three times before but this time she would be cheering on the runners.
"I've filled my bucket list," she said.
Jones, who works for the Cook County circuit court system, had salted-lime wedges ready for the runners because it helps runners with cramps, she said.
Jones said the crowd barriers were tighter this year. The increased security meant she would not be able to run a supportive stretch with her friends, Jones said.
"That was a big help," Jones said of her experience as a marathoner.
"It wasn't so secured," Jones said of the crowd barriers in years before the bombings. "You can't run out and say hi."
"It wasn't all that strict" in past years, Jones said. "I understand it, but it puts a damper on the whole process."
Jones said she especially liked having friends run alongside her on the final stretch, "Those 6.2 miles are the roughest."