Google Maps Mystery

Today I chased myself down a rabbit hole and haven’t emerged yet. Consequently I’m calling for help.

I was poking around Google Maps when I noticed a large grey-shaded area near where I live, shown in this screen capture. I have no idea what this is.

Let me eliminate some things for you so you’re not throwing items at me that are irrelevant:

• This area does not correspond to any administrative boundary such as a county or a city, or set of counties or cities
• This area isn’t a large commercial district
• This area is not owned by the government or part of a military reservation or whatever.
• This area is not the center of a local zombie incursion

The shaded area represents a largely residential area of north Cobb and south Cherokee counties. here are commercial areas, but nothing humongous.  I have no idea what this is. Is it simply an error, or a joke on Google’s part? ((This led me down the second rabbit hole of the day: it took until now for me to realize that Google Maps doesn’t have a legend. Weird, huh?))

So what is this? Prize to the winner.