The Midewin National Tallgrass Prairie, located in northern Illinois near the town of Joliet, was established in 1996 as the nation's first national tallgrass prairie. This 19,000-acre complex of 21 natural biological communities is administered by the U.S. Forest Service, in cooperation with the Illinois Department of Natural Resources and with the support of hundreds of volunteers and partner agencies, businesses and organizations.

Part of the former Joliet Army Ammunition Plant established in 1940, Midewin remained largely closed to the public while the Army cleaned contamination from decades of TNT manufacturing and packaging.

While Midewin's prairie landscape and habitat suitability have become degraded by invasion of alien species, conversion of many areas to agricultural uses, and the break-up of the extended ecosystem due to development of areas surrounding the site, the site still hosts a diversity of landscapes and habitats. Midewin's prairie complex includes dolomite prairies, one of the rarest natural communities in North America, in addition to grasslands, savanna, wetlands, seeps, upland forests and three streams.

These landscapes today provide habitat for 348 species of native plants, 108 species of breeding birds (149 species use the site for breeding, feeding, or wintering), 40 aquatic species, including 9 species of freshwater mussels, 23 species of reptiles and amphibians, 25 conservative insect species which require native plant communities to survive and 27 species of wild mammals.

Midewin provides crucial habitat for breeding Upland Sandpiper, Bell's Vireo, Bobolink, Dickcissel, Sedge Wren, Eastern Meadowlark, Henslow's and Grassshopper Sparrows, Baltimore and Orchard Orioles, Northern Mockingbird and Loggerhead Shrike.

During spring and fall migration, large numbers of migrant grassland and shrubland birds pause and rest at Midewin, while the small wetlands attract migratory rails, snipes, Marsh Wren and Swamp Sparrow.

This site was chosen as an IBA because it met the criteria for breeding Upland Sandpiper, Willow Flycatcher, Sedge Wren, Loggerhead Shrike, Bell's Vireo, Grasshopper Sparrow, and Bobolink.