Since the Middle Ages, European cities had been congested, dirty, and unhealthy. Industrialization greatly worsened these conditions. The steam engine freed industrialists from dependence on the energy of streams and rivers so that by 1800 there was every incentive to build new factories in cities, which had better shipping facilities and a large and ready workforce. Therefore, as industry grew, overcrowded and unhealthy cities expanded rapidly.

In the 1820s and 1830s people in Britain and France began to worry about the condition of their cities. Parks and open areas were almost nonexistent, and narrow houses were built wall to wall in long rows. Highly concentrated urban populations lived in extremely unsanitary conditions, with open drains and sewers flowing alongside or down the middle of unpaved streets.

The urban challenge — and the growth of socialist movements calling for radical change — eventually brought an energetic response from a generation of reformers. The most famous early reformer was Edwin Chadwick, a British official. Collecting detailed reports from local officials and publishing his findings in 1842, Chadwick concluded that the stinking excrement of communal outhouses could be carried off by water through sewers at less than one-twentieth the cost of removing it by hand. In 1848 Chadwick’s report became the basis of Great Britain’s first public health law, which created a national health board and gave cities broad authority to build modern sanitary systems. Such sanitary movements won dedicated supporters in the United States, France, and Germany from the 1840s on.

Early sanitary reformers were handicapped by the prevailing miasmatic theory of disease — the belief that people contract disease when they breathe foul odors. In the 1840s and 1850s keen observation by doctors and public health officials suggested that contagion spread through physical contact with filth and not by its odors, thus weakening the miasmatic idea. An understanding of how this occurred came out of the work of Louis Pasteur (1822–1895), who developed the germ theory of disease. By 1870 the work of Pasteur and others had demonstrated that specific living organisms caused specific diseases and that those organisms could be controlled. These discoveries led to the development of a number of effective vaccines. Surgeons also applied the germ theory in hospitals, sterilizing not only the wound but everything else that entered the operating room.

The achievements of the bacterial revolution coupled with the public health movement saved millions of lives, particularly after about 1890. In England, France, and Germany death rates declined dramatically, and diphtheria, typhoid, typhus, cholera, and yellow fever became vanishing diseases in the industrializing nations.

More effective urban planning after 1850 also improved the quality of urban life. France took the lead during the rule of Napoleon III (r. 1848–1870), who believed that rebuilding Paris would provide employment, improve living conditions, and glorify and strengthen his empire. Baron Georges Haussmann (1809–1884), whom Napoleon III placed in charge of Paris, destroyed the old medieval core of Paris to create broad tree-lined boulevards, long open vistas, monumental buildings, middle-class housing, parks, and improved sewers and aqueducts. The rebuilding of Paris stimulated urban development throughout Europe, particularly after 1870.

Mass public transportation was also of great importance in the improvement of urban living conditions. In the 1890s countries in North America and Europe adopted an American transit innovation, the electric streetcar. Millions of riders hopped on board during the workweek. On weekends and holidays streetcars carried city people on outings to parks and the countryside, racetracks, and music halls.2 Electric streetcars also gave people of modest means access to improved housing, as the still-crowded city was able to expand and become less congested.

Industrialization and the growth of global trade also led to urbanization outside of Europe. The tremendous appetite of industrializing nations for raw materials, food, and other goods caused the rapid growth of port cities and mining centers across the world. Many of these new cities consciously emulated European urban planning. For example, from 1880 to 1910 the Argentine capital of Buenos Aires modernized rapidly. The development of Buenos Aires was greatly stimulated by the arrival of many Italian and Spanish immigrants, part of a much larger wave of European migration in this period (see Chapter 27).