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In 2015, geologist Peter Rogerson recalculated the geographic center of Illinois, which had previously been determined in 1920 by the US Geological Survey (USGS), The USGS, Rogerson contended, had omitted important considerations, not least the curvature of the earth. the state's USGS-determined center-a point 1.5 miles southeast of the municipality of Rochester was inaccurate.