▁lot " ▁– ▁or ▁moder ately ▁sk illed ▁middle - class ▁occup ations ▁such ▁as ▁c ash iers , ▁typ ists , ▁w eld ers , ▁far mers , ▁app liance ▁repair men ▁– ▁decl ined ▁the ▁fur th est ▁in ▁w age ▁rates ▁and / or ▁numbers . ▁Emp loyment ▁requiring ▁either ▁more ▁skill ▁or ▁less ▁has ▁been ▁less ▁affected . ▁However ▁the ▁timing ▁of ▁the ▁great ▁techn ological ▁change ▁of ▁the ▁era ▁– ▁internet ▁use ▁by ▁business ▁starting ▁in ▁the ▁late ▁ 1 9 9 0 s ▁– ▁does ▁not ▁match ▁that ▁of ▁the ▁growth ▁of ▁income ▁inequality ▁( start ing ▁in ▁the ▁early ▁ 1 9 7 0 s ▁but ▁s lack ening ▁somewhat ▁in ▁the ▁ 1 9 9 0 s ). ▁Nor ▁does ▁the ▁introduction ▁of ▁techn ologies ▁that ▁increase ▁the ▁demand ▁for ▁more ▁sk illed ▁workers ▁seem ▁to ▁be ▁generally ▁associated ▁with ▁a ▁diver gence ▁in ▁household ▁income ▁among ▁the ▁population . ▁In vent ions ▁of ▁the ▁ 2 0 th ▁century ▁such ▁as ▁AC ▁electric ▁power , ▁the ▁autom obile , ▁air plane , ▁radio , ▁television , ▁the ▁was hing ▁machine , ▁X ero x ▁machine , ▁each ▁had ▁an ▁economic ▁impact ▁similar ▁to ▁computers , ▁micro process ors ▁and ▁internet , ▁but ▁did ▁not ▁co inci de ▁with ▁greater ▁inequality . ▁ ▁Another ▁explanation ▁is ▁that ▁the ▁combination ▁of ▁the ▁introduction ▁of ▁techn ologies ▁that ▁increase ▁the ▁demand ▁for ▁sk illed ▁workers , ▁and ▁the ▁failure ▁of ▁the ▁American ▁education ▁system ▁to ▁provide ▁a