▁Spo on ▁River ▁coming ▁from ▁F ult on ▁County ▁and ▁across ▁from ▁Brow ning , ▁it ▁is ▁joined ▁by ▁the ▁Sang am on ▁River , ▁which ▁passes ▁through ▁the ▁state ▁capital , ▁Spring field , ▁Illinois . ▁The ▁La ▁Mo ine ▁River ▁flows ▁into ▁it ▁approximately ▁ ▁south west ▁of ▁Be ard st own , ▁which ▁is ▁south ▁of ▁Pe oria ▁and ▁P ek in ▁and ▁north west ▁of ▁Lincoln ▁and ▁Spring field . ▁ ▁Near ▁the ▁confl u ence ▁of ▁the ▁Illinois ▁with ▁the ▁La ▁Mo ine ▁River , ▁it ▁turns ▁south , ▁flow ing ▁roughly ▁parallel ▁to ▁the ▁Mississippi ▁across ▁south western ▁Illinois . ▁Mac oup in ▁Creek ▁joins ▁the ▁Illinois ▁on ▁the ▁border ▁between ▁Gre ene ▁and ▁Jersey ▁count ies , ▁approximately ▁ ▁up stream ▁from ▁the ▁confl u ence ▁with ▁the ▁Mississippi ▁River . ▁ ▁For ▁the ▁last ▁ ▁of ▁its ▁course , ▁the ▁Illinois ▁is ▁separated ▁from ▁the ▁Mississippi ▁River ▁by ▁only ▁about ▁, ▁by ▁a ▁pen ins ula ▁of ▁land ▁that ▁makes ▁up ▁Cal h oun ▁County . ▁The ▁Illinois ▁joins ▁the ▁Mississippi ▁near ▁G raft on , ▁approximately ▁ ▁north west ▁of ▁dow nt own ▁St . ▁Louis ▁and ▁about ▁ ▁up stream ▁from ▁the ▁confl u ence ▁of ▁the ▁Missouri ▁River ▁and ▁the ▁Mississippi . ▁ ▁Ge ology ▁South ▁of ▁Hen ne pin , ▁the ▁Illinois ▁River ▁is ▁following ▁the ▁ancient ▁channel ▁of ▁the ▁Mississippi ▁River . ▁ ▁The ▁Ill ino ian ▁Stage , ▁about ▁ 3 0 0 , 0 0 0 ▁to ▁