The Illinois Basin is a geological region located in the central United States, primarily covering parts of the states of Illinois, Indiana, and Kentucky. It is known for its rich deposits of coal, oil, and natural gas, making it an important area for energy production. The basin formed during the Paleozoic era and features sedimentary rock layers that have accumulated over millions of years. This basin is also significant for its role in the Midwestern economy, providing resources for both local and national energy needs. Additionally, the Illinois Basin is home to various ecosystems and habitats, contributing to the region's biodiversity.