16. Garry McCarthy

« 15. Miles White17. Joe Mansueto » AGE: 52 OCCUPATION: Superintendent, Chicago Police Department The city’s top cop sets the agenda for crime fighting—and he has not been shy about exercising his influence. Within months of ditching Newark last August, he made good on his promise of change, shifting 1,000 officers from desk jobs to … Read more

15. Miles White

« 14. Jerry Reinsdorf16. Garry McCarthy » AGE: 56 OCCUPATION: Chairman and CEO, Abbott Laboratories Like Irene Rosenfeld (No. 12), White would have landed higher on our list had he not recently bowed to pressure from investors and announced he’ll snap his huge company in two. By the end of 2012, he’ll run Abbott’s $22 … Read more

14. Jerry Reinsdorf

« 13. Toni Preckwinkle15. Miles White » AGE: 76 OCCUPATION: Chairman, Chicago Bulls and White Sox; co-owner, United Center Arguably the most masterful negotiator the sports world has ever seen, Reinsdorf opened a restaurant adjacent to his publicly funded ballpark last year and handed taxpayers a $3.5 million bill. Meanwhile, over the past two years, … Read more

13. Toni Preckwinkle

« 12. Irene Rosenfeld14. Jerry Reinsdorf » AGE: 64 OCCUPATION: President, Cook County Board of Commissioners If Rahm gets bored with the mayor’s office, there may be no better successor than this formidable, unsentimental former alderman. She has reformed Cook County government by firing Todd Stroger’s cronies, rolling back a portion of his one-cent sales … Read more

11. Andrew Mason

« 10. Eric Lefkofsky12. Irene Rosenfeld » AGE: 31 OCCUPATION: Cofounder and CEO, Groupon Seizing on the power of collective buying via daily deals on the Internet may seem obvious now. But it’s from Mason’s brain that the multibillion-dollar idea sprang. The Northwestern grad, who cofounded Groupon four years ago with mentor and former employer … Read more

12. Irene Rosenfeld

« 11. Andrew Mason13. Toni Preckwinkle » AGE: 58 OCCUPATION: Chairman and CEO, Kraft Last year Fortune named this mac-and-cheese lover the single most powerful woman in American business. But Rosenfeld’s August decision to split Kraft into two companies—a $32 billion global snacks maker that she’ll helm and a slower-growing $16 billion North American grocery … Read more

100. Marc Weissbluth

« 99. Bill Daley  AGE: 69 OCCUPATION: Founder, Sleep Medicine Center at Children’s Memorial Hospital The author of Healthy Sleep Habits, Happy Child—the bible for bleary-eyed new parents now in its third edition—still works as a pediatrician on the Gold Coast. Getting an infant to sleep through the night? Now that’s power. MORE ON WEISSBLUTH: … Read more

10. Eric Lefkofsky

« 9. Grant Achatz11. Andrew Mason » AGE: 42 OCCUPATION: Cofounder and chairman, Groupon; tech investor If you listen to the skeptics, Groupon’s business is bound to slow; the deals are crummy; the stock is going nowhere. But let’s not forget that Lefkofsky and cofounders Andrew Mason (No. 11) and Brad Keywell (No. 21) pulled … Read more

1. Rahm Emanuel

 2. PATRICK FITZGERALD » AGE: 52 OCCUPATION: Mayor, City of Chicago In the ten months since he sailed into office on an endorsement from President Obama, our pugnacious mayor has proved he’s the city’s alpha male. Exhibit A: the 50–0 vote on his first budget in November, despite its painful cuts and fee hikes. He … Read more