There were numerous efforts to do this beginning in the 1700s; the most successful was the American Colonization Society and the establishment of Liberia, with Monrovia as its capitol; Liberia means Land of the Free and the capitol was named for James Monroe.
The motives behind these projects varied. Some felt that the freed slaves would be a danger, seeking revenge on their former masters. Some despised the blacks and wanted to rid America of their presence. Others had humanitarian intentions, as did, for the most part, the American Colonization Society. There were also efforts to evangelize the African continent and convert them to Christianity. They truly felt that they were saving their souls. Such was the story of Quamino, educated at Princeton in the 1770s with the intention of sending him to Africa as a missionary; instead, he fought in the Continental Navy when the Revolution broke out and was killed in battle.
Many different efforts included a colony in Canada, but the blacks, accustomed to the warm climates of the American South, were miserable and many became ill and died.
Those who were sent to Africa were several generations removed from their African ancestors and they were utterly lost in a strange land and an unfamiliar society.
It is strange to think that some humanitarians who thought slavery was evil opposed emancipation because the freed slaves had limited skills, were often illiterate, and depended on their masters for basic necessities. Others of course were virulent racists who would have preferred the freed slaves be eradicated from society by any means, including shipping them to various islands, or other continents.