Volume of traffic travelling on freeway lanes, outskirts of Washington DC, USA

air pollution american freeway automobiles backview backviews busy road busy roads carbon emissions carbon footprint city living conditions congested congestion district of columbia environmental damage exhaust emissions exit freeways fumes global warming going away going home highway highways homeward bound major routes many vehicles motorway normal traffic outskirts overpopulated polluting environment population explosion population growth roadway roadways rush hour rush hour traffic flow traffic flowing transport transportation trip vehicles back view cars daytime driving heading home heading off horizontal journey journeys motorways outdoors outside rear view stock image stock photo stock photograph the road ahead the way forward travel travel photo travel photograph travel photography travel stock travels travel destinations travel destination color image color colour tourism destination