industrial use clear cut land to place industrial plants hazardous waste produced thermal pollution water to hot chemical waste housing and development new subdivisions are cropping up due to population growth in areas land is cleared for commercial use large town with a growing suburbs depends on resources outside the city why are big cities growing increase in birth rates immigration poor are moving to larger cities and away from rural areas cities have grown from 2% to 45% since 1950 by 2050 66% of all [people in the world will live in urban areas heat islands enormous amounts of heat generated creates an urban heat island benefits better education medical services social service problems infectious diseases inadequate water system poor sewer systems exposure to pollution smart growth reduces dependence on cars controls and directs sprawl cuts wasteful resource use us cities portland oregon san francisco cali curtiba brazil europe compact cities cluster development new urbanism old villageism walkability mixed use and diversity quality ecocities or green cities protect biodiversity