Cultural diversity in the United States is a direct result of immigration. In fact, almost all ethnic groups in the country are products of immigration. For instance, the white majority in the United States are descendants of migrants from Europe. Likewise, most minority ethnic groups are descendants of migrants from other parts of the world namely Africa, South America, Asia, and North America (especially Mexico), among others. In essence, understanding the relations between ethnic groups in the United States requires a thorough look at the history of immigration. Consequently, this paper explores history of immigration and its timeline. The United States is majorly composed of immigrants. This happened in various timelines of its controversial history. In fact, United States’ immigration is considered special to the rest of the world. Firstly, no other country has ever experienced such great numbers of immigrants who came from every part of the world. Secondly, it provided jobs and alternatives for most immigrants. However, it is important to state that U.S. immigration has been quite controversial. Moreover, its immigration policy has raised eyebrows on its agenda. The policy has repeatedly failed to mitigate the type of immigrants and to control the number of immigrants entering the U.S. The first immigrants were mainly composed of British settlers (60%) who came between 1607 and 1776. During this period, there was no immigration policy. Most of these settlers came for economic and religious reasons. This period saw the coming of Germans who settled in Pennsylvania. They had their own culture and language. They were also quite controversial as they were seen as disloyal to mainstream Americans. The next batch that came into America during this period was African slaves. It is estimated that only roughly 500,000 slaves immigrated to the United Stated despite slave trade of between 11 and 12 million slaves of African descent to the greater Americas. Moreover, about 10% of Africans who lived in the North were free although they faced extreme discrimination. However, those in the South faced terrible conditions in slavery. A common characteristic of this state was continued revolts in the South. Incidentally, the first large-scale immigration was observed between 1820 and 1880. This encompassed over 10 million people. There was no immigration policy until in 1875 when the first control act was established. The first wave of immigration saw large immigration from Europe (especially the Irish and the Germans). They came mainly for economic reasons. The second large-scale (over 27.5 million) immigration happened between 1880 and 1930. Most migrants were from Southern and Eastern Europe (especially Italians, Poles, and Russians). They were poor and unskilled. They lived in concentrated areas. They also had their own customs, religion, and language. About 1 million Jews also migrated during this period. In contrast to their Eastern and Southern Europe counterparts, the Jews were skilled. However, they both faced discrimination in their newfound homes. This led to the establishment of an improved immigration act that tested potential immigrants on literacy (1917), restricted the total immigratio