The 71-year-old has hardly slowed down since leaving office in 2011. After serving as Chicago's mayor for six terms, he now fills his time working at a law firm and as a senior fellow at the University of Chicago.
Daley was in Arizona on business for the Katten Law Firm Friday when he began to feel ill, spokesperson Jackie Heard said. The former mayor was flown back to Chicago, and while airborne, Daley began to feel disoriented. As a precaution, an ambulance met the his plane upon landing. Heard told ABC7 Daley was able to walk to the ambulance.
Saturday, Daley was in the Intensive Care Unit (ICU) at Northwestern Memorial Hospital for monitoring and tests. He was said to be alert and was receiving guests in the hospital all day, even as doctors performed tests and monitored his condition.
"I wish Mayor Richard Daley a swift recovery. We're all praying for him,'' Illinois Gov, Pat Quinn wrote in a statement.
Daley had few medical concerns during his 22 years in office.
He was last hospitalized in December 2002 with flu symptoms, including severe dehydration. While he was there, doctors discovered Daley had an irregular heartbeat, or arrhythmia, and high blood pressure. He was given medication.
Earlier that year, Daley was hospitalized after he lost his balance and felt light headed at a restaurant. Doctors attributed the incident to cramps from exercising.
In 2011, doctors conducted extensive tests after Daley complained of chest pain, but they found no blockage.
ABC7Chicago.com will update this developing story as more information becomes available.