Half-marathons continue to lead race growth

Since 2003, half-marathons have been the fastest growing road race distance, and 2011 was no exception.

Of the 100 largest timed U.S. road races, half-marathons comprised 42 percent, according to figures from Colorado Springs, Colo.-based Running USA.

And the Competitor Group, producers of the Rock 'n' Roll series, had 15 of them.

The top 100 races had more than 1.6 million finishers, and five road races had more than 40,000 timed finishers each.

That compares to 922,500 total finishers in 2000.

The 100th race in 2000 had 3,600 finishers. In 2011, the 100th race had more than 8,000 finishers.

Here are the top 10 timed races:

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

2. Lilac Bloomsday Run 12K, 51,303 (Spokane)

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

4. ING New York City Marathon, 47,133

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

6. Bank of America Chicago Marathon, 35,755

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

8. Ukrop's Monument Avenue 10K, 33,365 (Richmond, Va.)

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

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

View the full list and other statistics at Running USA.