Nebraska is around the same size as South Dakota.

South Dakota is approximately 196,540 sq km, while Nebraska is approximately 199,099 sq km, making Nebraska 1% larger than South Dakota. Meanwhile, the population of South Dakota is ~814,180 people (1.0 million more people live in Nebraska).
Tip: This to-scale comparison of South Dakota vs. Nebraska uses the Mercator projection, which distorts the size of regions near the poles.