That's a pretty sweet map of population density
It actually isn't; there are shitloads of high density areas that don't show up dark purple, and shitloads of "Cows wear masks?!?!?!" zones lit up.
Look at the lit up zone in Central California along the Nevada border. It's more lit up than LA. Look at the Sonoma/Mendocino coast zones. Lit up.
Look at South Florida. The coastal strip is actually a bit less lit up, but the communities inland are brighter.
Look at the Northeast. East Shore Maryland. Fckng NOBODY lives there. Lit up. Western Massachusetts. There's nobody there. Lit up. Northern New Hampshire and what appears to be Dartmouth, lit up. Coastline, much less lit up.
I can't even find Cincinnati on this map. It should be lit up compared to the visible dark splotch on Lexington, KY. Same thing with Memphis. The 'burbs to the Southeast show up, but the city itself is on the river, and the river is NOT lit up. OKC/Tulsa are barely there. Biloxi and Gulfport are two of the larger places in Mississippi, but their Gulf Coast is very lightly shaded. To the North, there's more shading.
Look at Southwest Georgia. Columbus is on the Chattahoochee, but the state line with Alabama isn't very dark. Go a bit Southeast, and it's one of the darkest zones in the state, even more so than Metro ATL. But there's basically nothing there. What is so lit up? Jimmy Carter's house?
Look at all the lighter shades in North Jersey abutting NYC. That is some of the most densely populated real estate in the US.