
Rupp had been recovering from a surgery on his left foot to treat Haglund's deformity, a congenital bump on the heel which causes problems for the Achilles tendon. Galen Rupp had finished in fifth place the previous year in a time of 2:06:21 and said he "could not be more excited" to be running. In the men's race, defending champion Mo Farah returned, having run 2:05:11 in 2018 and 2:05:29 at the 2019 London Marathon in April. Not long before the day of the race, Gelete Burka, who had won the 2019 Paris Marathon and had run a personal best of 2:20:45, joined the field. Other competitors in the field included three-time Olympian Fionnuala McCormack and Amy Cragg, however, she later pulled out of the race in August due to a hamstring injury. Pérez had finished fourth in 2:24:44 at the 2017 Chicago Marathon, but did not finish the 2018 Boston Marathon. Saina ran a time of 2:22:56 to win in Paris, but had failed to finish the 2017 Tokyo Marathon or 2017 New York City Marathon. Hasay had finished third in the 2017 edition and third at the 2017 Boston Marathon, but had not competed at the 2018 Chicago Marathon or 2018 Boston Marathon due to two stress fractures in her foot. In the initial field, only three other women had run sub-2:25 before 2018 Paris Marathon winner Betsy Saina, Madaí Pérez who had run 2:22:59 in 2006, and Jordan Hasay, who ran 2:20:57 in 2017. Kosgei won the previous year and had finished either first or second in nine out of ten of the marathons in her career. The favorite in the women's race was Brigid Kosgei who had run a personal best of 2:18:20 at the 2019 London Marathon in April. There were 20 aid stations situated every one to two miles along the course. There is a slight uphill section after mile 26 before the course re-enters Grant Park to finish. The course continues south through Chinatown before turning north just after mile 23 back towards the downtown. The course continues down Jackson Boulevard then turns south through Little Italy and Pilsen before crossing the river again via Cermak Road. The course passes through Greektown on Adams Street before turning back east in the 16th mile. The runners cross the Chicago River via the Wells Street Bridge before re-crossing the river heading west via the Monroe Street Bridge. The course continues to Sheridan Road before turning back south along Broadway, passing through Boystown, Old Town, and River North. The course turns north onto LaSalle Street and enters Lincoln Park around mile 5. Before leaving the park, the course runs underneath the BP Pedestrian Bridge before entering Downtown Chicago where the runners go along Michigan Avenue, Grand Avenue, and State Street. The course starts and finishes in Grant Park. The marathon distance is officially 26.219 miles (42.195 km) long as sanctioned by World Athletics.
