I used data from Google Earth to collect and compile my grocery stores layer and I used the population centroids, based on the US Census data for both Palm Bay and West Melbourne. The US Census data indicated that the census blocks were farther apart as you traveled south from the center of Palm Bay. This meant to me that the population was much less dense. As I reviewed the aerials of south Palm Bay I discovered this area is very rural. If I did this lab exercise again, I would use a greater distance from a grocery store, perhaps five miles, for south Palm Bay, however, I would have to determine a definition to confidently say where Palm Bay turns rural.
I gained valuable experience using TileMill and then loading my Tiles (file extension = .mbtiles) to Mapbox. However, the link above tells us that TileMill is no longer in active development; looks like I'll be using Mapbox Studio Classic instead.As an Open Source program, Mapbox is constantly changing, so this made the lab a little more challenging. In the end I was able to compile a Mapbox Dataset that had a basemap and both my Food Desert and Grocery Store layers. Below is what my map looks like at this point.
As you can see, there appears to be a no grocery stores south of Malabar Road. That is why so much of Palm Bay is a Food Desert. I suspect that more grocery stores may move into south Palm Bay in the future.