During the nineteenth century, the United States experienced a period of rapid urbanization. The Industrial Revolution and the nation's change in status from a small, agricultural country to a major commercial and industrial power led to a massive change in the makeup of the American city. The scope of this writeup is not an American history lesson per se, but an exploration into the changes in cities and what effects these changes have today.
The pressures behind urbanization
At the beginning of the nineteenth century, most American cities still functioned as cities have for thousands of years. A very small proportion of the population was urban, because it took very close to the entire population to grow enough food to feed everyone. City growth has always depended very greatly on the efficiency of agriculture in a society. At first, a single person (or family) could grow no more food than they required; the entire population practiced agriculture, and they each worked to provide for their other, less pressing needs - clothing and other goods - as they could.
In America, the Industrial Revolution began just before the beginning of the 19th century. In 1800, 6% of the population of the nation lived in urban areas, and 85-90% of th population was engaged in agriculture. Over the ensuing century, the first figure rose to 40% and the latter dropped to 50% - which meant that each farmer could produce twice what they needed for themselves. The major increase in agricultural efficiency came from agricultural machinery. Large equipment made much of the manual labor of farming redundant. Thus a much smaller percentage of the population could meet the entire nation's agricultural needs.
Another pressure toward urbanization also stemmed from the Industrial Revolution: the switch from cottage industries to factories as the main production centers. Giant machines, largely powered by water power, became central to industry. Great numbers of people in a small area were needed to operate these machines. These people needed housing, and their presence supported commercial growth, including the innovative department store. Thus, there was a great economic incentive for cities to grow, and that incentive translated into jobs and higher (although still extremely low) wages for workers. Not only were workers lured in from the countryside, but these developments also supported a burgeoning immigrant population, which formed a large percentage of the population of the United States' major cities.
The third factor that promoted the urbanization of America during this period is the development of cheaper, faster methods of transportation during the early part of the 19th century. The steamboat and the railroad first became prominent during the 1820s and 1830s. During this period, an enormous number of railroads and canals appeared. These allowed cities to conduct trade with far larger markets, and the most dramatic effects were upon New York, in its role as the U.S.'s economic capital, and Chicago, which became the economic center of the newly-blossoming Midwest.
The results
Cities grew quickly, with huge influxes of population, largely poor, many of them foreigners, and much faster than city infrastructure and development could properly handle. Population density was extremely high, much higher than today, and large numbers of people lived in tenements. Tenement housing was dirty, crowded, noisy, and immensely unhealthful. Open septic tanks were the norm; sanitary sewers did not exist yet, and the storm sewers were nothing more than disease incubators. Cities were smelly and unpleasant. Manhattan, for example, had a population of 2.2 million residents by 1900, a density of 100,000 per square mile. Today, the population has dropped to 1.5 million, largely because people no longer tolerate those conditions.
As a matter of fact, disease was so rampant in 19th century cities that their natural population growth was negative - meaning that only because of migration, either from the countryside or from outside the U.S., did the population of cities grow. Large cities were ugly and dark, with very little greenery to relieve the grey of buildings. As the Industrial Revolution progressed, cities became polluted as well, and were noted only for their ugliness and the misery of their inhabitants.
This concentration was primarily due to the transportation of the era. The railroads and waterways that allowed cities to grow also constrained their growth, as the entire city had to be concentrated around these locations. The lack of automobiles meant that cities had to be entirely accessible on foot; thus, cities remained small, with almost all development within 3-4 miles of the city center.
Responses to the problems of city life
Toward the end of the 19th century, cities began to decentralize somewhat. First, the electric streetcar appeared in the 1880s, which allowed the city's radius to double. Suburbs began to grow around the perimeters of larger cities. Manufacturing followed, and factories slowly began to appear in suburban areas, where the land was considerably less constrained. Rising productivity and corresponding increases in income allowed people to buy larger dwellings and shorter workdays allowed them to spend more time traveling to and from work. The arrival of the automobile further increased the size of cities.
The density of cities also led to many concerted efforts to make cities more comfortable and healthy. In fact, the modern practice of urban planning arose toward the end of the 19th century, in large part to alleviate the difficulties of city life. First came laws mandating minimum standards for housing, starting with a regulation in New York in 1867. This was updated periodically, and in 1901 New York passed the landmark Tenement House Act, which mandated separate toilets for each apartment and larger courtyard areas, among other things.
Another area of major change was sanitation. Effective sanitary sewers were first developed in England around 1840, and they slowly found their way into American cities. They had the potential to make a huge impact on cities and the health of their citizens. Sewers, however, required major construction in already-built areas, and also required central planning of a sort that wasn't widespread in America, which believed in free-wheeling capitalism and a laissez-faire government. Prior to this period, cities were generally given very little say in their growth. Only the loosest of regulation was permitted to city government.
The rapidness of growth during this period spawned yet another change. Citizens began to call for the inclusion of open areas in cities. Parks were thought to provide 'ventilation', making cities not only more comfortable but safer, discouraging the damp and filth that fostered disease. Again, New York led the nation, with its enormous Central Park, designed in 1857 by Frederick Law Olmsted and Calvin Vaux. Other major cities quickly followed suit.
Out of this urban milieu, the modern profession of urban planning slowly developed. People, having witnessed the effects of unchecked, unregulated growth, saw the wisdom of allowing their governments to govern the growth of cities. Several disparate movements were the beginning of modern urban planning.
First was the civic improvement movement, which promoted tree planting, paving of streets, elimination of billboards, and other small changes. Those who espoused civic improvement wanted the government to spend money to improve cities. This was certainly not urban planning per se, but it made the populace more receptive to the idea. The civic art movement was another contributor; toward the end of the 19th century, large public works of art, structures designed strictly for their aesthetic appeal, began to appear in major cities.
The most important predecessor to modern urban planning, however, was the City Beautiful movement. This appeared in the wake of Chicago's 1983 Columbian Exposition in celebration of the four-hundredth anniversary of Christopher Columbus' arrival in the Americas. The fairgrounds were a beautiful example of the possibilities of city design: 700 acres of buildings, promenades, and landscaped areas combined into a splendid vision.
The result was a great degree of attention paid to the aesthetic aspects of city design. Certainly the City Beautiful movement doesn't come close to addressing all the issues behind modern urban planning, but it is very much ancestral to the modern practice. The City Beautiful movement led directly to the Plan of Chicago, which, created in 1909, can be said to be the first modern piece of urban planning - but at this point we leave the 19th century, and this becomes the material of another writeup.