Soon, producer services emerged as a fourth basic economic sector where routine low-wage service employment moved to low-cost sites and advanced corporate services centralized in cities.
Peagi tulid esile kvartenaarsed ehk tootmise teenused kui neljas majandussektor, kus rutiinsed madalapalgalised teenused liikusid väiksema kuluga aladele ning kõrgema tasemega korporatiivsed teenused koondusid linnadesse.