▁of ▁the ▁state ▁also ▁experienced ▁a ▁major ▁increase ; ▁many ▁veter ans ▁returned ▁to ▁Arizona ▁after ▁the ▁war ▁ended ▁in ▁ 1 9 4 5 , ▁lay ing ▁the ▁found ations ▁for ▁the ▁large ▁metropol ises ▁of ▁Phoenix ▁and ▁T uc son . ▁ ▁History ▁ ▁Econom ics ▁and ▁population ▁growth ▁Before ▁World ▁War ▁II , ▁Arizona ' s ▁main ▁source ▁of ▁income ▁was ▁generated ▁by ▁the ▁" F ive ▁C " ▁indust ries ▁– ▁cattle , ▁cot ton , ▁co pper , ▁cit rus , ▁and ▁climate ▁– ▁which ▁fl our ished ▁after ▁the ▁beginning ▁of ▁the ▁ 2 0 th ▁century ▁and ▁the ▁World ▁War ▁I - era . ▁However , ▁the ▁collapse ▁of ▁the ▁Stock ▁Market ▁in ▁ 1 9 2 9 ▁and ▁the ▁en su ing ▁de pression ▁eventually ▁put ▁the ▁state ▁into ▁a ▁period ▁of ▁decl ine . ▁According ▁to ▁James ▁E . ▁Sh erman , ▁the ▁beginning ▁of ▁the ▁De pression - era ▁created ▁a ▁whole ▁new ▁string ▁of ▁g host ▁towns ▁in ▁Arizona ▁as ▁people ▁left ▁to ▁find ▁opportunity ▁elsewhere . ▁The ▁situation ▁went ▁mostly ▁un changed ▁up ▁until ▁the ▁beginning ▁of ▁the ▁war ▁in ▁ 1 9 3 9 . ▁ ▁Once ▁it ▁seemed ▁as ▁though ▁inter vention ▁in ▁Europe ▁was ▁in ev itable , ▁the ▁federal ▁government ▁author ized ▁the ▁military ▁to ▁build ▁new ▁bases ▁in ▁Arizona , ▁which ▁would ▁be ▁used ▁mainly ▁for ▁training ▁purposes . ▁With ▁the ▁" overn ight " ▁construction ▁of ▁air fields ▁and ▁other ▁war - related ▁infrastr ucture