Northern Boundary, The
The marker is located 1-3/4 miles west of Plano on the south side of US 34.
No coordinates identified
Illinois Department of Transportation and The Illinois State Historical Society
The northern boundary of Illinois as prescribed in the Ordinance of 1787 was an east and west line from the southern tip of Lake Michigan at approximately 41 degrees, 37 minutes passing through this region to the Mississippi River. When Illinois applied for admission into the Union the bill included this boundary. While the measure was still pending in the House, Nathaniel Pope, the Illinois delegate in Congress, felt the necessity of giving Illinois a firm footing on the lake thus committing her interest to northern commerce through the lakes to off-set the influence of the southern trade on the Mississippi and Ohio Rivers in case of future internal conflict. Pope felt that the territorial addition would, 'afford additional security to the perpetuity of the Union, inasmuch as the State would thereby be connected with the states of Indiana, Ohio, Pennsylvania, and New York, through the Lakes.' The amendment introduced by Pope making the boundary 42 degrees, 30 minutes, passed easily and the Enabling Act was approved on April 18, 1818. Illinois gained approximately 61 miles of added territory including 14 counties covering 8500 square miles of fertile soil, lake and river ports, and such future prosperous cities as Chicago, Rockford, Freeport, and Galena. Politically, this additional northern territory decisively influenced Illinois in favor of national unity and against slavery during the Civil War period and was important in the nomination of Abraham Lincoln in 1860. Thus Pope's foresight had national repercussions as well as significance for Illinois.
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