The Royal Gorge is a canyon of the Arkansas River located west of Cañon City, Colorado. The canyon begins at the mouth of Grape Creek about 2 mi west of central Cañon City and continues in a west-northwesterly direction for approximately 6 mi until ending near U.S. Route 50. Being one of the deepest canyons in Colorado, it is also known as the Grand Canyon of the Arkansas (River), with a maximum depth of 1,250 ft. The canyon is also very narrow, measuring from 50 ft wide at its base to 300 ft wide at its top, as it carves a path through the granite formations below Fremont Peak and YMCA Mountain, which rise above the north and south rims, respectively.  The Arkansas River is a major tributary of the Mississippi River. It generally flows to the east and southeast as it traverses the states of Colorado, Kansas, Oklahoma, and Arkansas. The river's source basin lies in the western United States in Colorado, specifically the Arkansas River Valley, where the headwaters derive from the snowpack in the Sawatch and Mosquito mountain ranges. It then flows east into the Midwest via Kansas, and finally into the South through Oklahoma and Arkansas.