Center of the Nation Series is a six day event series that takes place in a different state each day. Day one (1) of the series takes place in beautiful Sterling, Colorado within Pioneer Park. PR Chasers, Trail Runners. Taking place in Pioneer Park, this flat and gravel multi-loop trail isn’t one that’s particularly scenic, however, is one that offers the opportunity to chase PRs! Sterling itself is a vibrant city in northeastern Colorado known largely for its agriculture and educational institutions. While it may not be the most bustling, activity-rich destination, it’s a great visit for those travelling out of state to participate.