Immigration has shaped the United States as a nation since the first newcomers arrived over 400 years ago. Beyond being a powerful demographic force responsible for how the country and its population became what they are today, immigration has contributed deeply to many of the economic, social, and political processes that are foundational to the United States as a nation.
Although immigration has occurred throughout American history, large-scale immigration has occurred during just four peak periods: the peopling of the original colonies, westward expansion during the middle of the 19th century, and the rise of cities at the turn of the 20th century. The fourth peak period began in the 1970s and continues today.
These peak immigration periods have coincided with fundamental transformations of the American economy. The first saw the dawn of European settlement in the Americas. The second allowed the young United States to transition from a colonial to an agricultural economy. The industrial revolution gave rise to a manufacturing economy during the third peak period, propelling America's rise to become the leading power in the world. Today's large-scale immigration has coincided with globalization and the last stages of transformation from a manufacturing to a 21st century knowledge-based economy. As before, immigration has been prompted by economic transformation, just as it is helping the United States adapt to new economic realities.