p>In the late-nineteenth and early twentieth centuries, reformers began fighting for clean air, clean water, and public health improvements. Women's groups often led the campaigns. Many progressive reformers believed that good citizenship was related to environmental improvements and contact with nature.

Reformers pushed for reduction of pollution and for construction of urban parks and playgrounds. Businessmen, reformers, and urban professionals such as engineers and public health officials worked together for improvements in the water supply and sanitary services. As transportation moved from horse-driven carriages to electric trolleys, automobiles, and trucks, there were substantial improvements in street and air sanitation. In general, campaigns for clean air and reduction of waterway pollution were largely unsuccessful. Any improvement in urban areas shifted the problem downstream, with growing automobile congestion due to urban sprawl.

Source: The City and the Natural Environment
By Joel A. Tarr, Global Development Research Center, CC BY-SA 4.0