The name 'Rust Belt' came about due to the decline of industry in the 1970s, when many of the region's factories had been closed, and the resulting shuttered buildings were guarded only by rusting gates.

The Industrial Heartland attracted a huge number of immigrants from 1890-1930. The Polish came in droves, especially to Pittsburgh and the Chicago-Milwaukee area. Italians immigrated also, explaining why eight of the 24 Mafia families in America were located in the region. Some other immigrants were Irish, Greek, Slovak, Slovenian, Lituanian, and Hungarian, among others. African-Americans came from the Southern U.S. looking for opportunity as well. All of these people were added to the German and Scots-Irish population that was already present in the area. Echoes of this diversity in the Industrial Heartland today are heard in radio shows and various festivals.

After the steel mill closed the coke works continued to be operated under the name New Boston Coke. This operation closed in 2002 but here are the remaining coke ovens and coal processing building that remain. The metal doors on the ovens have been removed, leaving the refractory brick lining of the ovens naked.
http://www.coalcampusa.com/rustbelt/
http://en.wikipedia.org/wiki/Rust_belt