Urban renewal programs strive to upgrade areas that are becoming slums.
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The wheels of the first road vehicles were fashioned from crude stone disks.
Despitetheproliferationofotherfastermodesoftransportation,therailroadsremainthelargestcarriersofintercityfreightintheUnitedStates.
TheNativeAmericaninterpreterSacajaweawasavaluablememberoftheLewisanddarkexpeditionin1805.