Dark red = at least one per every 800k people.
Medium red = one per everyone 800k-a million people
Light red = one per every million to 1.25 million people.
Light blue = one per every 1.25 million to 1.75 million people.
Medium blue = one per every 1.75 million to 2.5 million people
Dark blue = one per over 2.5 million people
Gray = No Apple Stores
Hawaii has the best ratio, one Apple Store per every 458,270 people. Indiana meanwhile has one for every 3,258,461 people, the worst amongst states that have them.