Tokyo was knocked out in the second round.
That left just Rio and Madrid still in the mix. The IOC voted again to separate the two and elected a winner, which will be announced by IOC president Jacques Rogge later Friday.
Madrid's surprising success in reaching the final round came after former IOC president Juan Antonio Samaranch made an unusual appeal for the Spanish capital, reminding the IOC members as he asked for their vote that, at age 89, "I am very near the end of my time."
Chicago's elimination was one of the most shocking defeats in IOC voting history. It had long been seen as a front-runner and got the highest possible level of support - from President Barack Obama himself.
But the emotional appeals from Obama and his wife Michelle - they both flew to Copenhagen to fight in Chicago's corner - fell on deaf ears in the European-dominated IOC. The IOC's last two experiences in the United States were marred by controversy: the 2002 Salt Lake City Winter Olympics were sullied by a bribery scandal and logistical problems and a bombing hit the 1996 Games in Atlanta.
