Density, I would suspect, has a great deal to do with it. And it only makes sense. The closer proximity you have to more people, the greater the risk of them passing anything on to you. Compare New York to California-- similar populations in the metro areas but the more suburbanized and expansive character of CA (compared to NY's tenements) means the virus just doesn't spread the same way. In Minnesota, Hennepin county (where Minneapolis is) has (by far) the most cases. And it is the densest county in Minnesota. Rural counties (counties, not cities) have far fewer cases-- sometimes less than twenty total cases.
If Tyson treats their workers the same way they treat their supply, I'd suspect one would find those plants to be quite dense as well.