Sinceworldwarii,theUnitedStatesontheworldeconomyhasalwaysmaintainedtheleadingposition.Theenterpriseinordertomeettheever-changingcompetitionandsurvivalenvironment,accordingtothecostandefficiencydon'tbreaktheproductiondepartment,theproductionlink,andeventheproductionelementstoadjustandkeepcompetitive,additionalvaluehigherdepartmentsandindustry.TheUnitedStateseconomicstructureafterindustryseniorchangeadjusted,someprimaryproductssuchasdailynecessities,rawmaterialsandworkingandindustrialproductionofsemi-finishedproductsaretransferredtodevelopingcountries,andtheseproductsandtheproductionandlivingconsumptionwillneed,whichdeterminesthattheUnitedStatesimportsfromtheinternationalmarketaretheprimaryindustryproducts