The Bolder Boulder 10K race will host 55,000 runners during the one day event. The race kicked off at 7 a.m. Monday.
Ninety-one waves of runners weaved through the rolling hills of Boulder, all making their way to the finish line at Folsom Field.
For many, the race has become a family tradition, one that dates back to 1978, when the race first began.
"When I first started running, I did it myself," Karyn Harkrader said laughing. "Then it became a family affair. We finished dead last, though"
The 10k race also has a fresh start this year. Race organizers moved the starting line about a mile south, making the start and finish lines only about a mile apart.
They weren't trying to make the race any harder. Organizers say they were just trying to make it easier for everyone to get around on race day, spending less time stuck in traffic and parking.
The Bolder Boulder is held every Memorial Day and features runners, walkers and wheelchair racers of all ages. It is the largest race in the U-S in which all participants are timed and it is the 5th largest road race in the world.
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