Final answer:
Cities exhibit economies of scale which provide benefits such as efficient production and services. However, they also face challenges like traffic congestion and pollution which lead to negative environmental impacts.
Step-by-step explanation:
The environmental impact of big cities is neither entirely positive nor entirely negative. While cities are examples of economies of scale, providing economic benefits such as efficient production due to a large group of nearby customers, a substantial labor pool, and a concentration of suppliers and specialists, they also face challenges. Some of these include traffic congestion, which can nullify the advantages of geographical proximity by increasing travel times, and high densities leading to pollution, overcrowding in public facilities, and potential upticks in crime rates due to anonymity. Thus, while the economic advantages of big cities attract people and activities, the accompanying negative impacts on the environment and quality of life serve as a deterrent, preventing the formation of one giant city.