History The United States acquired this territory following its victory in the Mexican–American War in 1848. It was originally part of the New Mexico Territory established at the time. In 1863, during the American Civil War, Congress established the Arizona Territory to improve regional administration. It operated until 1912 when it was admitted as a state.
hisTory tHe uniTED sTaTes aCQuiReD thiS teRrITorY FolLOWing ItS viCtory In the MExicAN–AmeriCAn wAr In 1848. iT was oriGinally Part of tHe new mexiCO territOry estABlIshed at thE timE. IN 1863, duriNG ThE americAN civil WAr, CoNgress estaBLIShed the ariZoNA TerriTOry TO iMprove regional administRation. it oPEratEd unTiL 1912 when it waS adMITTed as A STATE.