High Quality Content by WIKIPEDIA articles! The Cache River is a 92-mile-long (148 km) waterway in southernmost Illinois, in a region sometimes called Little Egypt. The basin spans 737 square miles (1,910 km2) and six counties: Alexander, Johnson, Massac, Pope, Pulaski and Union. Located at the convergence of four major physiographic regions, the river is part of the largest complex of wetlands in Illinois. The Cache River Wetlands — America`s northernmost cypress/tupelo swamp — harbors 91 percent of the state’s high quality swamp and wetland communities. It provides habitat for more than 100 threatened and endangered species in Illinois. In 1996, the Cache was designated a Wetland of International Importance by the Ramsar Convention.