Principal Meridians and Baselines in Illinois

Description of Map

• The 2nd Principal Meridian runs north-south through Indiana.
• The 3rd Principal Meridian runs north-south through Illinois
  along the western edge of Jefferson County (southern Illinois).
• The Baseline used with the 2nd and 3rd Meridians runs east-west
  along the northern edge of Jefferson County, Illinois.

• The 4th Principal Meridian runs north-south through Illinois
  along the eastern edge of Schuyler, McDonough, Warren and Mercer Counties, Illinois.
• The Baseline used with the 4th Meridian runs through Schuyler, Brown and Adams Counties,beginning at the intersection of the 4th Meridian with the Illinois River in Schuyler County.