As we all know, the United States didn't have a colonial empire in Africa. Instead while European empires were looking south towards Africa, the US was looking west towards the pacific ocean, annexing several islands in the pacific ocean (most notably Hawaii and the Philippines).
But what if the United States had decided to build up a colonial empire in Africa. Given the racist stance the US took towards Pacific islanders in denying them the right to vote, I don't think there would be any major objective to doing so with Africans especially if they had some limited self-rule. I could see a natural progression. Liberia, instead of becoming an independent nation state becomes a US protectorate, dependency, colony, possession or some other legal category controlled by the United States.
With the full muscle of the US military backing Liberia, it's likely Liberia wouldn't lose substantial territory to Sierra Leone (UK) and the Ivory Coast (France) as it did in OTL. When the scramble for Africa came, I imagine the US would be in a good position to grab greater territory in West Africa.
Is this a realistic scenario? How big of a colonial Empire could the US have gained? What would be the likely consequences of an American empire in Africa.