Niger dwarfs North America: about 1,185,111 km² km² against 24,710,000 km² km². At true size Niger is about 20.9× larger — the whole of North America fits into Niger roughly 20 times.
The old Mercator map treated both about equally (1.1× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Niger fits 20× into North America.