K-51 begins at the Colorado state line, acting as a continuation of County Road M. The highway travels due east through fields. K-51 then turns north onto K-27, forming a 10 mile (16 km) long concurrency. K-27 leaves at Richfield. K-51 runs eastward for a few miles before heading south towards Rolla. In Rolla, US-56 is met, and K-51 turns east onto US-56, crossing into Stevens County. Both routes then pick up northbound K-25, with all three routes heading into Hugoton. In the city itself, US-56 and K-25 turn north, leaving K-51 to head east on its own. The route goes eastward, entering Seward County. K-51 comes to an end north of Liberal at US-83.