The vast majority of people I’ve seen in Africa (in every country I’ve been to except perhaps South Africa) wear either African traditional dress or – less expensive – used American clothes.
I just listened to an interesting description of the process by which the clothes make it to Africa in Rivoli’s The Travels of a T-shirt in the Global Economy: people donate to the Salvation Army, they pick out what they can sell in their shops and sell the rest to US merchant, who sorts some to send abroad (the best) and the rest to go into mattress stuffing (and like products). A big African merchant buys a gigantic bundle of clothes, which he sells to the vendors I see in the African markets. (Rivoli argues convincingly that this is the only point at which textiles face a genuinely free market.)
Different countries have different words for it: in Tanzania the used clothes are called mitumba (in Swahili), in Sierra Leone they are called junks (in Krio).
Below is a photo of one of my favorites, from the ferry stand in Freetown. [I spoke with the gentleman: he’s never seen Napolean Dynamite, and I doubt he’s ever voted for Pedro.]