People give too much weight to overall sparsity/density, discounting how much human behavior has a role in creating personal density even in seemingly sparse areas. You can see massive infections in very sparse rural areas so long as people are congregating and not taking precautions. That seems to be what's happening in Nebraska.

Behavior matters more. Here in Manhattan we're past the peak solely because of changes in behavior. It doesn't matter how sense the built environment is when most people are barely leaving their homes.

New arrivals including domestic flights to Hawaii are being subject to heavy quarantine with follow-up, requirements of full documentation of where you will be staying, etc.

https://hidot.hawaii.gov/blog/2020/04/24/improved-verificati...

They do not have the hospital capacity for this getting out of control.