American Colonization Society (ACS), originally known as the Society for the Colonization of Free People of Color of America until 1837, was founded in 1816 by Robert Finley to encourage and support the migration of free African Americans to the continent of Africa.

The American Colonization Society was founded in response to what was seen as a growing social problem: what to do with free Blacks. The number of free people of color grew steadily following the American Revolutionary War, from 60,000 in 1790 to 300,000 by 1830.:26 Slaveowners feared that these free Blacks might help their slaves to escape or rebel. In addition, many white Americans believed that African Americans were an inferior race, and, therefore, should be relocated to a place where they could live in peace, a place where they would not encounter prejudice, a place where they could be citizens.The African-American community and the abolitionist movement overwhelmingly opposed the project. In most cases, African Americans' families had lived in the United States for generations, and their prevailing sentiment was that they were no more African than white Americans were European. Contrary to claims which stated that their emigration was voluntary, many African Americans, both free and enslaved, were pressured into emigrating.:343 Indeed, enslavers sometimes manumitted their slaves on condition that the freedmen leave the country immediately.According to historian Marc Leepson, "Colonization proved to be a giant failure, doing nothing to stem the forces that brought the nation to Civil War." Between 1821 and 1847, only a few thousand African Americans, out of millions in the US, emigrated to what would become Liberia. By 1833 the Society had transported to the future Liberia 2,769 individuals, while the increase in Black population in the U.S. during those same years was about 500,000. Close to half of them died from tropical diseases. In addition, the transportation of the emigrants to the African continent, including the provisioning of requisite tools and supplies, proved very expensive.Starting in the 1830s, the Society was met with great hostility from white abolitionists, led by Gerrit Smith, who had supported the Society financially, and William Lloyd Garrison, author of Thoughts on African Colonization (1832), in which he proclaimed the Society a fraud. According to Garrison and his many followers, the Society was not a solution to the problem of American slaveryit actually was helping, and was intended to help, to preserve it.

African Americans (also referred to as Black Americans and formerly Afro-Americans) are an ethnic group consisting of Americans with partial or total ancestry from any of the black racial groups of Africa. The term "African American" generally denotes descendants of enslaved Africans who are from the United States. While some Black immigrants or their children may also come to identify as African-American, the majority of first generation immigrants do not, preferring to identify with their nation of origin.African Americans constitute the second largest racial group in the U.S. after White Americans, as well as the third largest ethnic group after Hispanic and Latino Americans. Most African Americans are descendants of enslaved people within the boundaries of the present United States. On average, African Americans are of West/Central African with some European descent; some also have Native American and other ancestry.According to U.S. Census Bureau data, African immigrants generally do not self-identify as African American. The overwhelming majority of African immigrants identify instead with their own respective ethnicities (~95%). Immigrants from some Caribbean and Latin American nations and their descendants may or may not also self-identify with the term.African-American history began in the 16th century, with Africans from West Africa being sold to European slave traders and transported across the Atlantic to the Thirteen Colonies. After arriving in the Americas, they were sold as slaves to European colonists and put to work on plantations, particularly in the southern colonies. A few were able to achieve freedom through manumission or escape and founded independent communities before and during the American Revolution.

After the United States was founded in 1783, most Black people continued to be enslaved, being most concentrated in the American South, with four million enslaved only liberated during and at the end of the Civil War in 1865. During Reconstruction, they gained citizenship and the right to vote, but due to White supremacy, they were largely treated as second-class citizens and found themselves soon disenfranchised in the South. These circumstances changed due to participation in the military conflicts of the United States, substantial migration out of the South, the elimination of legal racial segregation, and the civil rights movement which sought political and social freedom. In 2008, Barack Obama became the first African American to be elected President of the United States.