Term: meridian (survey)
Definition: an imaginary north-south line from which subsequent surveys started; Wisconsin is laid out from the Fourth Principal Meridian, and every location is measured as east or west of it.
[Source: More information about the G.L.O. survey in Wisconsin as well as digital images of the surveyors" original field notes are at http://libtext.library.wisc.edu/SurveyNotes/]
