ulated ▁places ▁in ▁N ey riz ▁County <0x0A> </s> ▁Campbell ▁County ▁is ▁a ▁county ▁in ▁the ▁U . S . ▁state ▁of ▁South ▁Dak ota . ▁As ▁of ▁the ▁ 2 0 1 0 ▁census , ▁the ▁population ▁was ▁ 1 , 4 6 6 , ▁making ▁it ▁the ▁fifth - le ast ▁popul ous ▁county ▁in ▁South ▁Dak ota . ▁Its ▁county ▁seat ▁is ▁M ound ▁City . ▁ ▁The ▁county ▁was ▁created ▁in ▁ 1 8 7 3 ▁and ▁organized ▁in ▁ 1 8 8 4 . ▁It ▁was ▁named ▁for ▁Norman ▁B . ▁Campbell , ▁a ▁Dak ota ▁Territ ory ▁legisl ator ▁in ▁ 1 8 7 3 ▁and ▁son ▁of ▁General ▁Charles ▁T . ▁Campbell . ▁ ▁History ▁Campbell ▁County ▁was ▁formed ▁in ▁ 1 8 7 3 ▁and ▁organized ▁in ▁ 1 8 8 4 . ▁La ▁Grace ▁served ▁as ▁the ▁first ▁county ▁seat ; ▁in ▁ 1 8 8 8 ▁the ▁seat ▁was ▁transferred ▁to ▁M ound ▁City . ▁ ▁Geography ▁Campbell ▁County ▁lies ▁on ▁the ▁north ▁side ▁of ▁South ▁Dak ota ; ▁its ▁north ▁boundary ▁line ▁ab uts ▁the ▁south ▁boundary ▁line ▁of ▁the ▁state ▁of ▁North ▁Dak ota . ▁The ▁Missouri ▁River ▁flows ▁south ward ▁along ▁the ▁county ' s ▁west ▁boundary ▁line . ▁The ▁county ▁terrain ▁consists ▁of ▁semi - ar id ▁low ▁rolling ▁hills , ▁a ▁portion ▁of ▁which ▁is ▁dedicated ▁to ▁agricult ure . ▁The ▁terrain ▁s lop es ▁to ▁the ▁south ▁and ▁east , ▁with ▁its ▁highest ▁point ▁occurr ing ▁on