Mexico is about 10 times bigger than South Dakota.

South Dakota is approximately 196,540 sq km, while Mexico is approximately 1,964,375 sq km, making Mexico 899% larger than South Dakota. Meanwhile, the population of South Dakota is ~814,180 people (128.3 million more people live in Mexico).
Tip: This to-scale comparison of South Dakota vs. Mexico uses the Mercator projection, which distorts the size of regions near the poles.