South Dakota never locked down. It might be interesting to see how well they do against similar States that did lock down.
South Dakota is sparsely populated - whole population of the state is less than 900,000 people. Rapid City population 75,000; Sioux Falls pop 180,000. It has none of the densely packed urban centres that are conducive to rapid spread of an infectious disease (e.g. New York City). From that point of view, their situation of never having locked down is probably justified ... for now.
Other western farming states without huge cities in them - Wyoming, Montana, North Dakota - are in basically the same situation.
Iowa, Nebraska, Minnesota, Wisconsin, Colorado each contain at least one big city, and they're somewhat worse off, although nothing like the northeast or south.