The most McIsolated location in the contiguous U.S. is just north of Glad Valley, South Dakota, and is 145 miles by car to the nearest McNuggets six piece.
I love how you can see U.S. settlement patterns just from a map of McDonalds locations. The major cities are obvious hubs, but even cooler are the gaps — you can distinctly see the Okefenokee as a small gap in Southern Georgia, and then at the bottom edge of Florida, just above the Key West McDonalds, you can see where the Everglades are.
As for the gap midway up the east coast, I guess that’s maybe Albermarle sound, in North Carolina? You can very clearly follow down the coast from New York-Pennsylvania-Baltimore/D.C.-Richmond-Virginia Beach, so south of that, at the point that juts out most eastward, would be about right. Plus the little pinchers that stick out around the gap would be the barrier islands around it. I find it curious you could see Albermarle Sound clearly, though, while Chesapeake Bay, which is much bigger, is barely a thin wriggle.
You can also see a big gap in the West Virginia mountains (the Monongohela?), the only McGap of its size anywhere on the east. You’ve also got a gap at the Adirondacks farther up north, and below that, there’s a jutting squiggle… It’s about the right place for the Allegheny National Forest, but the shape of it doesn’t seem quite right, so not entirely sure what explains the lack of Maccas there.
Unfortunately, I’m not familiar enough with the west portion of the U.S. to really pick out any features, but it is cool how you can very clearly see the skeleton of the interstate system dotted out. You can see a few on the east, too — check out 1-20 stretching out east from Dallas towards Atlanta, and I-81 between Knoxville and Richmond — but they’re not as clear.
And around North Dakota, it totally starts to look like a bunch of cells in the midst of mitosis. Maybe that’s how McDonalds chains reproduce.