Mardi Gras in New Orleans and other Gulf Coastal cities in Louisiana, Mississippi, & Alabama.
You nailed it. Just look at the cases in the outlying counties from metro Detroit (Wayne, Oakland and Macomb) at the number of confirmed cases. That alone gives you a good perspective of what happens with a concentrated populus.
New Orleans had their annual drunkfest and two weeks later... A blowout. South Florida had their beach blanket party for the spoiled college crowd, 2 weeks later a mini blowout, mini because those kids spread it far and wide.
When our governor mandated a stay at home and don't travel to your summer cottage up north, it was with a good reason. All you had to do was look at a Michigan map and you could plainly see the rates of infection and how it spread... Right up 75 and 23 going north to the upper lower and the UP.
While I don't agree with a lot of her political leanings, I do agree with her Covid mandates 100%. I think she could have used a bit more diplomacy in enacting them but when dealing with idiots, sometimes you have to be blunt.
In Northern Michigan the hospital capacity as well as medical staffing is very sparse because it's very lightly populated. They don't need, nor want the people from downstate bring the virus with them and infecting everyone, they don't have an effective means to deal with it in the first place.
We have very limited cases here as well because of the rural setting and limited population. Any cases around here, the infected got it elsewhere, not locally.