Wikipedia
Americo-Liberians are a Liberian ethnicity of African-American descent. The sister ethnic group of Americo-Liberians are the Sierra Leone Creole people, who are of African-American, West Indian, and liberated African descent. Americo-Liberians trace their ancestry to free-born and formerly enslaved African Americans who immigrated in the 19th century to become the founders of the state of Liberia. They identified there as Americo Liberians. (Some African Americans, following resettlement in Canada, also participated as founding settlers in Sierra Leone and present-day Côte d'Ivoire.)
Later in Liberia, these African Americans integrated 5,000 liberated Africans called Congos (former slaves from the Congo Basins, who were freed by British and Americans from slave ships after the prohibition of the African slave trade) and 500 Barbadian immigrants into the hegemony. Unlike the Sierra Leone Creoles, Americo-Liberians rarely intermarried with indigenous West Africans.
The colonists and their descendants led the political, social, cultural and economic sectors of the country; they ruled the new nation for over 130 years as a dominant minority. From 1878 to 1980, the Republic of Liberia was a one-party state ruled by the Americo-Liberian-dominated True Whig Party and Masonic Order of Liberia.