Immigration to the United States
The United States has often been referred to as a nation of immigrants and with good reason. Practically every person living the United States is descended from someone who originally emigrated from another country. Over time, the volume of immigrants who have arrived in the United States and the countries of origin of immigrants have varied. Certain trends regarding immigration have emerged. Up until the 1840s, immigration remained relatively small. In 1847, the number of immigrants arriving in the United States passed the 200,000 mark for the first time. The highest rate of immigration to the United States took place between 1847 and 1854. The average annual volume of immigration remained at just under 435,000 from 1847 through 1930. Immigration once again peaked during the years between 1900 and 1914. During this time nearly 900,000 immigrants made their way to the United States per year. There was another rise in immigration between the 1980s and the 1990s.

Four Distinct Periods in the History of Immigration
There are four distinct periods that can be identified in the history of immigration to the United States. Prior to 1881, the majority of immigrants came from northwest Europe, primarily Ireland, Great Britain, Scandinavia and Germany. Throughout the colonial period, most immigrants were from Britain. Between 1881 and 1893 there was a distinctive transition in immigration. Following 1881, the number of immigrants arriving from eastern, southern and central Europe began to increase at a rapid rate. As World War I began in 1914, there was another transition. Beginning in 1915 and continuing until present times, a significant source of immigration to the United States has been from the Western Hemisphere. Immigrants arriving from Europe began to substantially decline beginning during the 1960s. That volume was replaced by a much more significant percentage of immigrants arriving from Asia. Throughout the course of United States history, immigration sources have transitioned from northwestern Europe to eastern, central and southern Europe to Asia.

Five Factors Play an Important Role in Immigration
Historians have pointed out that there is not a single factor that has led to immigration to the United States. As many as five factors are believed to play an important role in immigration. These factors include the availability of higher wages in the United States, degree of industrialization within an immigrant's home country, the number of previous immigrants arriving from that region or country, the rate of population growth in the preceding years and political and economic conditions in the U.S. Fluctuations in the amount of immigration to the United States are primarily due to changes in political and economic conditions in the U.S. Periods of low volumes of immigration have typically coincided with economic depressions in the United States or during times when there was significant immigrant discrimination. For instance, the volume of immigration to the United States declined in the 1930s during the Great Depression. During the 1920s, restrictions on immigration were imposed by the United States. Since that time, the volume of immigration to the U.S. has been continually subjected to a more direct determination by the government.