After the mid-nineteenth century, the development of machine-powered mass-manufacturing techniques powered the American economy.

As late as the eighteenth century, the great bulk of people in Europe and North America were still supporting themselves and their families through their individual labor, mostly on farmlands.

The demographic revolution that began in the Western world during the eighteenth century and accelerated during the nineteenth and twentieth centuries made it imperative to develop employment for the increasing numbers of people in the developing nations.

With each immigration wave that the United States has experienced, the culture and context of life in the United States have changed considerably.

This first major change in U.S. quota policy greatly altered the ethnic makeup of immigrants entering the United States during the late twentieth and early twenty-first centuries and prompted a massive increase in total immigration.

The act represented the first major attempt to restrict immigration into the United States.

Many countries, including the United States, are undergoing serious demographic transformations as a result of changing global migration patterns. Immigrants bring with them customs, practices and behavior patterns different fromthose of the receiving countries.

Mandated by the U.S. Constitution, the decennial censuses were originally undertaken for the purpose of apportioning congressional seats, electoral votes in presidential elections, and funding of government programs among the states.