Which state is the only one that borders just one other state?

From which country did the United States buy the Louisiana Territory in 1803? From which country did the United States acquire Florida by treaty in 1819? Which Secretary of State arranged the purchase of Alaska, once mocked as his "Folly"? Which four states meet at the Four Corners? Which two states border the most other states, with eight each? Which state is divided into "parishes" instead of counties? Which state is divided into "boroughs" instead of counties? Which state has a unicameral (one-house) legislature?