The Greenland Trail 50K is a trail race located on the front range of Colorado . It was started with the intent to kick off the trail running season by offering a variety of distances to suit your running needs. Run in the Greenland Open Space of southern Douglas County , the Greenland Trail 50K strives to be the premier 50K in Colorado. The race is limited to 550 runners and has filled the last two years. So, please register early!