Traffic on freeway, outskirts of Washington DC, USA

air pollution american freeway automobiles busy road busy roads carbon emissions carbon footprint city living city outskirts congested traffic congestion district of columbia environmental damage exhaust emissions flowing traffic freeways global warming headlights on highway highways homeward bound major routes many vehicles motorway overpopulated polluting environment population explosion population growth road trip rush hour rush hour streetlamps streetlights traffic conditions traffic flow traffic fumes traffic lanes transport transportation vehicles volume of traffic cars coming towards daytime driving heading home headlamps on horizontal journey journeys motorways outdoors outside stock image stock photo stock photograph travel travel photo travel photograph travel photography travel stock travelling travels travel destinations travel destination color image color colour tourism destination