The Rust Belt, formerly the Steel Belt or Factory Belt, is an area of the United States that underwent substantial industrial decline in the late 20th century. The region is centered in the Great Lakes and Mid Atlantic regions of the United States. Common definitions of the Rust Belt include Ohio, Indiana, Northern Illinois, southeastern Wisconsin, Michigan, Pennsylvania, and Upstate New York. Some broader geographic definitions of the region include parts of Central Illinois, Iowa, Kentucky, Maryland, Minnesota, Missouri, New Jersey, and West Virginia. The term "Rust Belt" is considered to be a pejorative by some people in the region.
Between the late 19th century and late 20th century, the Rust Belt formed the industrial heartland of the country, and its economies were largely based on iron and steel, automobile manufacturing, coal mining, and the processing of raw materials. The term "Rust Belt", derived from the substance rust, refers to the socially corrosive effects of economic decline, population loss, and urban decay attributable to deindustrialization. The term gained popularity in the U.S. beginning in the 1980s, when it was commonly contrasted with the Sun Belt, whose economy was then thriving.