Thousands of runners participate in the Bank of America Chicago Marathon on October 9, 2011 in Chicago, Illinois.
Race officials said Monday they'd reached the 45,000 runner threshold for this fall's Bank of America Chicago Marathon.
And that limit was reached in a record-setting six days, 25 days faster than last year, which was a record at the time.
Ten years ago, registration maxed out in 35 weeks, organizers said.
Those who still wish to run but missed out on making the registration can still take part through the marathon's charity program. Visit ChicagoMarathon.com for program information.
Registration for the 2012 Bank of America Chicago Marathon opened to the public at noon last Wednesday. The race itself is Oct. 7.