Cities became garbage pits By the early 1900s, most large cities suffered the unbearable smell of horse dung and urine. The stink of human waste and garbage also filled the air. Coal-burning fireplaces and factories created London's famous "pea soup" fog. This provided a mysterious backdrop for the detective stories of Sherlock Holmes, but it was a serious health problem. Advances in transportation sparked changes in city life. In early 19th-century cities, dense populations tended to live within walking distance from factories. The wealthy, however, could afford to take carriages from their suburban homes. In the late 1800s and early 1900s, suburban railroads and streetcars began to encourage the spread of urban areas. However, this type of
This article is available at 5 reading levels at https://newsela.com. commuting remained too expensive for working-class people until prices were gradually lowered. Among the suburbs radiating outward, the newest were usually limited to the wealthy. Older, less desirable suburbs were affordable to the middle class. Still older and more run-down districts were generally filled with working-class homes. Advances in transportation created huge traffic jams. The roads were packed with wagons, horses and people on foot. To deal with this problem, large cities such as Paris and New York began to develop subways, elevated trains and other public transportation systems.