Forgottonia (also spelled Forgotonia) is the name given to a 14 county region in Western Illinois in the late 1960s and early 1970s. This geographic region forms the distinctive western bulge of Illinois that is roughly equivalent to "The Tract," the Illinois portion of the Military Tract of 1812, along and west of the Fourth Principal Meridian. See Principal meridian. Since this region lies between the Illinois and Mississippi rivers, it is somewhat isolated (river bridge access) from the eastern portion of Central Illinois. See Illinois River bridges.
Variously described as a new U.S. state or an independent republic, Forgottonia eventually became a fictional political secession movement in the early 1970s conceived by residents of McDonough County, in the heart of this region. Western Illinois University student Neil Gamm was named governor, and the hamlet of Fandon near Colchester was to be Forgottonia's capital. The name would catch on because the region appeared to be "forgotten" by developers.