Africa dwarfs United States: about 30,370,000 km² km² against 9,439,424 km² km². At true size Africa is about 3.2× larger — the whole of United States fits into Africa roughly 3 times.
The old Mercator map treated both about equally (1× vs 2× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
United States fits 3× into Africa.