Missouri is about 2.1 times smaller than Japan.

Japan is approximately 377,915 sq km, while Missouri is approximately 178,414 sq km, making Missouri 47.21% the size of Japan. Meanwhile, the population of Japan is ~123.4 million people (117.1 million fewer people live in Missouri).
Tip: This to-scale comparison of Japan vs. Missouri uses the Mercator projection, which distorts the size of regions near the poles.
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