Today marks the end of an era for the Chicago Mercantile Exchange and the Chicago Board of Trade (CME merged with CBOT in 2007). For more than 160 years, the open outcry pits were a raucous and noisy place where people in colorful jackets jockeyed and shouted orders for commodities like corn, cattle, and pork bellies. Today, 99% of trading volume occurs electronically and all but one of the futures pits have been closed.
During its heyday, the noise on the floor was so loud that traders developed a system of sign language to be able to communicate their orders. In this video, traders Jim Hensel and Patrick Walsh translate this language used on the floor at the Chicago Board of Trade. The footage was shot by Skip Blumberg and Patrick Creadon for Chicago Slices in 1993.
More information and a historical timeline from PBS Newshour.