The Bolder Boulder is an annual 10-kilometer run in Boulder, Colorado. The 2007 race featured over 54,000 runners, walkers, and wheelchair racers, making it the second largest 10k race in the US and the fifth largest road race in the world. It has one of the largest non-marathon prize purses in road racing.

The 10K run is a long-distance road running competition over a distance of ten kilometres. Also referred to as the 10K road race, 10 km, or simply 10K, it is one of the most common types of road running event, alongside the shorter 5K and longer half marathon and marathon. It is usually distinguished from the 10,000 metres track running event by stating the distance in kilometres, rather than metres.