2001 20thcentury 20thcenturybritishhistory aircraft airplanes architecture biography bluecollarworkers buildingtrades business careers cars cityplanning commercial communications construction criticalcare disastermanagementpolicies ecosystems emergency emergencymedicalservices emergencymedicine environmentalscience fiction firesciencetechnology forestry forests general greatbritain greatplains heavyindustry helicopters historicalfiction history howthingswork humanservices hygiene industrialbuildings industrialhealth industryprofiles inventions inventors labormovement laborstudies loc localhistory london machinery mid-atlantic miscellaneous mountainstates naturaldisasters newjersey newyorkcity occupations physics public regionalbritishhistory rescue safety september11thterroristattacks state transportation trees trucking trucks unions unitedstate unitedstates unitedstatesstudies urban/metropolitanplanningpolicies urbandesign workingclass worldwarii