North Dakota is about 1.2 times bigger than Illinois.

Illinois is approximately 143,961 sq km, while North Dakota is approximately 178,647 sq km, making North Dakota 24% larger than Illinois. Meanwhile, the population of Illinois is ~12.7 million people (11.9 million fewer people live in North Dakota).
Tip: This to-scale comparison of Illinois vs. North Dakota uses the Mercator projection, which distorts the size of regions near the poles.
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