Grand Canyon is a valley in Warren County in the U.S. state of Missouri. The valley is an approximately four mile section of Charrette Creek which has a relatively wide floodplain between high canyon walls. The north end of the "canyon" is at 38°43′18″N 91°05′21″W / 38.72167°N 91.08917°W and the south or downstream end is at 38°39′32″N 91°06′14″W / 38.6…Grand Canyon is a valley in Warren County in the U.S. state of Missouri. The valley is an approximately four mile section of Charrette Creek which has a relatively wide floodplain between high canyon walls. The north end of the "canyon" is at 38°43′18″N 91°05′21″W / 38.72167°N 91.08917°W and the south or downstream end is at 38°39′32″N 91°06′14″W / 38.65889°N 91.10389°W.