1. Atlanta Journal-Constitution Peachtree Road Race 10K, Atlanta 55,077

2. Lilac Bloomsday Run 12K, Spokane, Wash.. 51,303

3. Dick’s Sporting Goods Bolder Boulder 10K, , Boulder, Colo. 49,213

4. ING New York City Marathon, New York 47,133

5. Zazzle Bay to Breakers 12K, San Francisco. 43,954

6. Bank of America Chicago Marathon, Chicago. 35,755

7. Cooper River Bridge Run 10K, Charleston, S.C. 34,789

8. Ukrop’s Monument Avenue 10K, Richmond, Va. 33,365

9. Zappos.com Rock ‘n’ Roll Las Vegas Half-Marathon,Las Vegas 33,257,

10. Bank of America Shamrock Shuffle 8K, Chicago. 32,442

11. OneAmerica 500 Festival Half-Marathon, Indianapolis, Ind. 30,659

12. Blue Cross Broad Street Run 10 Mile, Philadelphia 25,244

13. Boston Marathon, Boston 23,913

14. Pat’s Run 4.2 Mile, Tempe, Ariz. 22,676

15. Army Ten-Miler, Washington, D.C. 22,049

16. Country Music Half-Marathon, Nashville, Tenn. 22,015

17. Walt Disney World Half-Marathon, Orlando, Fla. 21,991

18. Marine Corps Marathon, Washington, D.C. 21,042

19. Honda LA Marathon, Los Angeles 19,902

20. Rock ‘n’ Roll San Antonio Half-Marathon, San Antonio, Texas. 19,546

SOURCE: Running USA. (Statistics from 2011 are the most current available.)