The reigning Boston champ is hoping to one up last year's second-place finish in the Windy City.
That year, Khalid Khannouchi set the world record.
Registration for 45,000+ runner race closes in a record six days.
Patrick Makau and Edna Kiplagat are at the top of the list.
There are three ways an athlete can qualify for America's most exclusive marathon.
One doctor found a way to make use of the heavy piece of metal.
The U.S. women's soccer star ran part of the Chicago Marathon to raise money for charity.
He hopes to run a faster marathon when he returns to the U.S.
The Russian wins for the third time in the Windy City.
The Kenyan ran the fastest marathon ever on U.S. soil.