I am looking for USA population density maps with sufficient granularity to see the variations in my neighborhood, like in people per square mile.
Does anyone know why what a Google search for "population density map" as a second hit gives me "USA Population Density Map" shortened URL https://arcg.is/1r90fn0 but when I view the map, all I see is a map with aerial land views and a singular red object "Charles Gill Elementary" and layers that only have one thing" Charles Gill Elementary, but no population density. Charles Gill Elementary is a school in Dallas, Tx.
And if this is an issue, how does it get fixed?
Using a Search Engine (Google, Bing, etc) to look for data is probably not the best way to approach this. That particular app you're finding is just owned by a user who works at the school mentioned, and hasn't been updated in over 4 years.
I would start your search over at the Living Atlas. If you can't find what you need there, then you can look at Data.gov, or go straight to the Census, since they will have this kind of information.