No cars are allowed on the most adorable official US Highway

The M-185 was actually built in the 1910's, a good 20 years after motor vehicles were banned all across Mackinac Island, a ban that remains in place to this day-- as the story goes, the local doctor had brought over a newfangled automobile, but because it was so noisy, it scared the rest of the residents' horses-- their complaints prompted the ordinance. Because Mackinac is so small and has had a history of being a tourist/vacation destination (for a few years, it was a National Park; in fact, it was the second one in the whole country, after Yellowstone), there was never a great need for cars. M-185 was declared a state highway in 1933, and actually remained unpaved until the 1950's.

So how does one use the highway, exactly? It's open to foot traffic, bikes, and horse-drawn carriages, which makes it a really pleasant route to take. They even pick up litter in a horse-drawn wagon! Another advantage is that the road, which at points is either called "Main Street" or "Lake Shore Road", has a picture-perfect route that loops around the whole coast of the island. You'll pass by natural features, like Arch Rock and an allegedly-haunted cave that locals call "The Devil's Kitchen", historic sites, like the spot where the British landed during the Battle of Mackinac Island during the War of 1812, and tons of other features unique to the island.