The area around Collinsville, Illinois, is the self-styled "horseradish capital of the world." The open stretch of agricultural land in the northeast of the American Bottom (roughly a 2,000-acre area between Horseshoe Lake and the limestone bluffs) produces 60% of the world's horseradish—with upward of 85% of the world's production occurring in the southern Illinois region. Much of this product is ground and exported to Germany and China—where the specific American Bottom heat is a delicacy. Potash, distributed over millennia by the meanders of the Mississippi and Missouri Rivers, is the key soil ingredient for the spiciest horseradish. Armoracia rusticana—as horseradish is known to the botanical world—is a labor-intensive crop, which may be why growing has been consolidated to about a dozen famers in a three-county area of the American Bottom. Every June since 1988, Collinsville has helds its annual International Horseradish Festival—with booths, tastings, and naughty root-themed t-shirts. Also not to be missed: just atop the bluffs from the farmland sits the Brooks Catsup Bottle Water Tower—the world's largest ketchup bottle—which is listed on the National Register of Historic Places.