Though the period is often associated with rampant economic expansion and growth, the United States experienced a number of major social, economic, and political problems during the late nineteenth century. Indeed, most of these problems happened not in spite of growth, but as a consequence of it. One major economic problem was related to the expansion and growth of massive corporations and conglomerates, of which John D. Rockefeller's Standard Oil Trust was the archetype. These trusts placed a large swath of the economy in the hands of a relatively few people.
A social issue emerging during the late nineteenth century was the rapid urbanization of the nation. This was a function of many factors, including the development of large industries in cities, as well as massive immigration. Many cities faced demographic crises during the period, as swarms of people crowded into neighborhoods, and buildings, that were not equipped to handle them. Crime, poverty, and sanitation emerged as major issues confronting late nineteenth century cities in places like New York and Chicago.
A somewhat related political issue during the period was the emergence of sophisticated political machines that controlled politics at the city level, and, increasingly, at the state level. New York City's infamous Tammany Hall was only one of the powerful machines that translated their power into graft, embezzlement, and other forms of corruption. Many machines, such as the Republican Stalwarts, even became so powerful that they could influence politics at the national level. Each of these developments became major targets of Progressives at the end of the century and into the twentieth century.