image usgs_drg_il_41087_h6 Illinois 41.875N 87.625W Chicago Loop o 2.438400 0.000000 0.000000 -2.438400 437103.091016 4650556.498898 H6 1988 1997 2006-10-10 USGS DRG o map of Illinois 41.875N 87.625W H6 Chicago Loop maps_usgs usgs_il jared@redjar.org 1997-01-01 2006-10-10