South Carolina is about 13 times smaller than Mauritania.

Mauritania is approximately 1,030,700 sq km, while South Carolina is approximately 77,983 sq km, making South Carolina 7.57% the size of Mauritania. Meanwhile, the population of Mauritania is ~4.2 million people (463,439 more people live in South Carolina).
Tip: This to-scale comparison of Mauritania vs. South Carolina uses the Mercator projection, which distorts the size of regions near the poles.