European nations came together at the
order to draw boundaries for the African colonies. These later
became the various African nations political borders.

Berlin Conference

Explanation:

Berlin Conference of 1884–1885 Meeting at which the major European powers negotiated and formalized claims to territory in Africa; also called the Berlin West Africa Conference.

source:  oxford reference

in 1862, president lincoln's emancipation proclamation opened the door for african americans to enlist in the union army. although many had wanted to join the war effort earlier, they were prohibited from enlisting by a federal law dating back to 1792.

explanation:

barrio is a spanish word meaning neighborhood. in spain, several latin american countries and the philippines, the term is also used officially to denote a division of a municipality while a ghetto is a part of a city in which members of a minority group live, typically as a result of social, legal, or economic pressure. the term may have originally been used in venice to describe the part of the city to which jews were restricted and segregated.