There have been several waves of immigration in American history.

The first migration climax occurred from 1820 to 1860, during which the total number of immigrants reached 5 million. Immigrants mainly come from western Europe and northern Europe, including about 2 million Irish, 6,543,800 Germans and a large number of African slaves sold to the United States. At the same time, some immigrants came from Asia, mainly from China, and they came to the United States to look for gold.

The second immigration climax was from 186 1 to 1880, and about 5 million immigrants came to the United States. After the end of the Civil War, the United States ushered in the peak of industrialization, and the demand for labor was strong. In order to attract European immigrants to the United States, 1864, President Lincoln lobbied Congress to pass the immigration encouragement bill. Secretary Seward even issued a circular to American diplomats in Europe, asking them to make attracting European immigrants one of the most important diplomatic tasks. In order to recruit skilled workers from Europe to work in the United States, some enterprises also send delegations to Europe for recruitment. They advertised in many European newspapers and published pamphlets to describe the attractive prospects of the United States to Europeans with immigration aspirations. Some enterprises also provide necessary travel expenses for Europeans who are willing to immigrate to the United States.

The third climax was from 188 1 to 1920, and the number of immigrants soared to 23.5 million. The migration peak is 1907, reaching 1285000. At this stage, the American government has repeatedly legislated to restrict European immigrants and exclude Asian immigrants. The growth of "old immigrants" from northwest European countries such as Britain, Germany and Sweden is limited, while the growth of "new immigrants" from southeast European countries such as Italy and Russia is rapid.

After these three immigration climaxes, 1920, the total population of the United States exceeded 1 100 million for the first time. From 1820 to 1920, the number of immigrants accounted for more than 20% of the annual population growth in the United States. These three waves of immigrants in American history not only had a far-reaching impact on the formation of American national character, but also made the United States rise rapidly in just over a hundred years, replacing Britain as the world's number one economic power and laying the foundation for becoming a world superpower in the future. It can be said that the immigration tide has made America strong.