Alex Ramsey (l.) and Patrick Sweeney are running the Chicago Marathon and then running to New York for that city's marathon. View Full Caption Scott Kummer

CHICAGO — For almost everyone, finishing the Chicago Marathon represents the completion of an epic challenge.

For Patrick Sweeney and Alex Ramsey, it's just a warmup.

The two ultrarunners will begin an 846-mile Chicago-to-New York running jaunt at Sunday's Chicago Marathon. When they cross the finish line in Grant Park, they're just going to keep running — for another 23 miles or so to Beverly Shores, Ind.

Ramsey, 30, said the pair will travel nearly 850 miles over 21 days — over mostly side roads and no highways — reaching the Big Apple in time for Nov. 1's New York City Marathon.

"I very much look forward to the opportunity of seeing this part of the country, and I'm just stoked to have this amount of time to run and do it with my buddy Pat," said Ramsey, an Ohio native currently living in Texas who usually runs barefoot.

Said Sweeney, 36: "Alex is at the top of the list of people I would like to do this trip with."

In less than 2 weeks Barefoot Alex Ramsey and I will begin our trek fro Chicago to New York to show solidarity... http://t.co/n752MwJVHg — Patrick Sweeney (@Bourbonfeet) September 29, 2015

Justin Breen says they'll have to run over a marathon a day:

Ramsey and Sweeney, of California, are flying into Chicago on Friday and staying in Bronzeville with Scott Kummer, a veteran long-distance runner who founded the group Flatlander Ultrarunners.

"It's an honor to have them in my city and to host them in my home," Kummer said. "More importantly I am honored to share them with my local running community. To me, they are the real stars of the running world."

Ramsey and Sweeney were recently part of a small group of runners who ran 3,080 miles across the United States starting in California. Ramsey took a path across the southern part of the country, finishing in Washington D.C., while Sweeney continued and completed his cross-country route in Boston. In that journey, to raise funds for the 100 Mile Club charity, they averaged running a marathon a day for well more than 100 days, Ramsey said.

"The difference this time is we're sort of under a deadline," Sweeney said. "But it's about staying in your limits. The human body is pretty amazing. From running across the country, it wasn't easy at first, but the body adjusts and figures out what it needs, and you find your comfort level."

They'll have a car to accompany them on their trip, packed with supplies, including food and water, and tents. Ramsey said they'll also be staying in hotels occasionally.

The pair are running for the "Walk for Peace" charity, which seeks to stop violence in Kenya and raise money for a "Peace School."

"This is very grass roots," Ramsey said. "This is our opportunity to spread peace."

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