In both Europe and the United States, the surge of industry during the mid- and late 19th century was accompanied by rapid population growth, unfettered business enterprise, great speculative profits, and public failures in managing the unwanted physical consequences of development. Giant sprawling cities developed during this era, exhibiting the luxuries of wealth and the meanness of poverty in sharp juxtaposition. Eventually the corruption and exploitation of the era gave rise to the Progressive movement, of which city planning formed a part. The slums, congestion, disorder, ugliness, and threat of disease provoked a reaction in which sanitation improvement was the first demand. Significant betterment of public health resulted from engineering improvements in water supply and sewerage, which were essential to the further growth of urban populations. Later in the century the first housing reform measures were enacted. The early regulatory laws (such as Great Britain’s Public Health Act of 1848 and the New York State Tenement House Act of 1879) set minimal standards for housing construction. Implementation, however, occurred only slowly, as governments did not provide funding for upgrading existing dwellings, nor did the minimal rent-paying ability of slum dwellers offer incentives for landlords to improve their buildings. Nevertheless, housing improvement occurred as new structures were erected, and new legislation continued to raise standards, often in response to the exposés of investigators and activists such as Jacob Riis in the United States and Charles Booth in England.

Also during the Progressive era, which extended through the early 20th century, efforts to improve the urban environment emerged from recognition of the need for recreation. Parks were developed to provide visual relief and places for healthful play or relaxation. Later, playgrounds were carved out in congested areas, and facilities for games and sports were established not only for children but also for adults, whose workdays gradually shortened. Supporters of the parks movement believed that the opportunity for outdoor recreation would have a civilizing effect on the working classes, who were otherwise consigned to overcrowded housing and unhealthful workplaces. New York’s Central Park, envisioned in the 1850s and designed by architects Calvert Vaux and Frederick Law Olmsted, became a widely imitated model. Among its contributions were the separation of pedestrian and vehicular traffic, the creation of a romantic landscape within the heart of the city, and a demonstration that the creation of parks could greatly enhance real-estate values in their surroundings. (See landscape architecture.)

Concern for the appearance of the city had long been manifest in Europe, in the imperial tradition of court and palace and in the central plazas and great buildings of church and state. In Paris during the Second Empire (1852–70), Georges-Eugène, Baron Haussmann, became the greatest of the planners on a grand scale, advocating straight arterial boulevards, advantageous vistas, and a symmetry of squares and radiating roads. The resulting urban form was widely emulated throughout the rest of continental Europe. Haussmann’s efforts went well beyond beautification, however; essentially they broke down the barriers to commerce presented by medieval Paris, modernizing the city so as to enable the efficient transportation of goods as well as the rapid mobilization of military troops. His designs involved the demolition of antiquated tenement structures and their replacement by new apartment houses intended for a wealthier clientele, the construction of transportation corridors and commercial space that broke up residential neighbourhoods, and the displacement of poor people from centrally located areas. Haussmann’s methods provided a template by which urban redevelopment programs would operate in Europe and the United States until nearly the end of the 20th century, and they would extend their influence in much of the developing world after that.

As the grandeur of the European vision took root in the United States through the City Beautiful movement, its showpiece became the World’s Columbian Exposition of 1893, developed in Chicago according to principles set out by American architect Daniel Burnham. The architectural style of the exposition established an ideal that many cities imitated. Thus, the archetype of the City Beautiful—characterized by grand malls and majestically sited civic buildings in Greco-Roman architecture—was replicated in civic centres and boulevards throughout the country, contrasting with and in protest against the surrounding disorder and ugliness. However, diffusion of the model in the United States was limited by the much more restricted power of the state (in contrast to European counterparts) and by the City Beautiful model’s weak potential for enhancing businesses’ profitability.

Whereas Haussmann’s approach was especially influential on the European continent and in the design of American civic centres, it was the utopian concept of the garden city, first described by British social reformer Ebenezer Howard in his book Garden Cities of To-Morrow (1902), that shaped the appearance of residential areas in the United States and Great Britain. Essentially a suburban form, Howard’s garden city incorporated low-rise homes on winding streets and culs-de-sac, the separation of commerce from residences, and plentiful open space lush with greenery. Howard called for a “cooperative commonwealth” in which rises in property values would be shared by the community, open land would be communally held, and manufacturing and retail establishments would be clustered within a short distance of residences. Successors abandoned Howard’s socialist ideals but held on to the residential design form established in the two new towns built during Howard’s lifetime (Letchworth and Welwyn Garden City), ultimately imitating the garden city model of winding roads and ample greenery in the forming of the modern suburban subdivision.

Perhaps the single most influential factor in shaping the physical form of the contemporary city was transportation technology. The evolution of transport modes from foot and horse to mechanized vehicles facilitated tremendous urban territorial expansion. Workers were able to live far from their jobs, and goods could move quickly from point of production to market. However, automobiles and buses rapidly congested the streets in the older parts of cities. By threatening strangulation of traffic, they dramatized the need to establish new kinds of orderly circulation systems. Increasingly, transportation networks became the focus of planning activities, especially as subway systems were constructed in New York, London, and Paris at the beginning of the 20th century. To accommodate increased traffic, municipalities invested heavily in widening and extending roads. (See also traffic control.)

Many city governments established planning departments during the first third of the 20th century. The year 1909 was a milestone in the establishment of urban planning as a modern governmental function: it saw the passage of Britain’s first town-planning act and, in the United States, the first national conference on city planning, the publication of Burnham’s plan for Chicago, and the appointment of Chicago’s Plan Commission (the first recognized planning agency in the United States, however, was created in Hartford, Connecticut, in 1907). Germany, Sweden, and other European countries also developed planning administration and law at this time.

The colonial powers transported European concepts of city planning to the cities of the developing world. The result was often a new city planned according to Western principles of beauty and separation of uses, adjacent to unplanned settlements both new and old, subject to all the ills of the medieval European city. New Delhi, India, epitomizes this form of development. Built according to the scheme devised by the British planners Edwin Lutyens and Herbert Baker, it grew up cheek by jowl with the tangled streets of Old Delhi. At the same time, the old city, while less salubrious, offered its inhabitants a sense of community, historical continuity, and a functionality more suited to their way of life. The same pattern repeated itself throughout the British-ruled territories, where African capitals such as Nairobi, Kenya, and Salisbury, Southern Rhodesia (now Harare, Zimbabwe), were similarly designed to accommodate their white colonial rulers. Although the decorative motifs imposed by France in its colonial capitals reflected a somewhat different aesthetic sensibility, French planners likewise implanted broad boulevards and European-style housing in their colonial outposts.