▁the ▁county ' s ▁north ▁boundary ▁line , ▁toward ▁the ▁NE ▁corner : ▁ 2 , 0 6 0 ' ▁( 6 2 8 m ). ▁The ▁county ▁has ▁a ▁total ▁area ▁of ▁, ▁of ▁which ▁ ▁is ▁land ▁and ▁ ▁( 4 . 8 %) ▁is ▁water . ▁ ▁The ▁eastern ▁portion ▁of ▁South ▁Dak ota ' s ▁count ies ▁( 4 8 ▁of ▁ 6 6 ) ▁observe ▁Central ▁Time ; ▁the ▁western ▁count ies ▁( 1 8 ▁of ▁ 6 6 ) ▁observe ▁Mountain ▁Time . ▁Campbell ▁County ▁is ▁the ▁western most ▁of ▁the ▁SD ▁count ies ▁to ▁observe ▁Central ▁Time . ▁ ▁Major ▁High ways ▁▁▁ ▁U . S . ▁Highway ▁ 8 3 ▁▁ ▁South ▁Dak ota ▁Highway ▁ 1 0 ▁▁ ▁South ▁Dak ota ▁Highway ▁ 2 7 1 ▁▁ ▁South ▁Dak ota ▁Highway ▁ 1 8 0 4 ▁ ▁Ad j acent ▁Count ies ▁▁ ▁Em m ons ▁County , ▁North ▁Dak ota ▁- ▁north ▁ ▁Mc Int osh ▁County , ▁North ▁Dak ota ▁- ▁n ortheast ▁ ▁Mc Ph erson ▁County ▁- ▁east ▁ ▁Wal worth ▁County ▁- ▁south ▁ ▁C ors on ▁County ▁- ▁west ▁( bound ary ▁of ▁Mountain ▁Time ) ▁ ▁Prote cted ▁areas ▁▁ ▁P oc asse ▁National ▁Wild life ▁Ref uge ▁ ▁Rog o ▁Bay ▁State ▁Game ▁Production ▁Area ▁ ▁Salt ▁Lake ▁State ▁Game ▁Production ▁Area ▁ ▁Sand ▁Lake ▁State ▁Game ▁Production ▁Area ▁ ▁Shaw ▁Creek ▁State ▁L akes ide ▁Use ▁Area ▁ ▁West ▁Pol lock ▁State ▁Rec re ation