The Willcox Playa is a large endorheic dry lake or sink (playa) adjacent to Willcox, Arizona in Cochise County, in the southeast corner of the state. It is part of the Sonoran Desert ecoregion and is the remnant of a Pleistocene era pluvial Lake Cochise. Portions of the dry lake bed have been used as a bombing range by the US military. It was designated a National Natural Landmark in 1966 for its fossil pollen captured underground, the thousands of sandhill cranes that roost in the area and the largest diversity of tiger beetles in the United States.