Yupp I do hear about this too, the state of Lincoln which are at east Washington merging with north Idaho become the state of Lincoln, also south Oregon and north California was planned to be merge together and become the state of Jefferson, but they have been proposed for long time. Also I heard California might split up itself due to its population, but I don't really know about this, alos I know Texas have the right to split itself up, but never had done yet.
I would love to see states, especially western states, to split up because all of the states in the western are too big to travel through while the New England area (northeast US) have very small states and are easy to travel through, also other reason why I would love to see states split up so we can have more choices which states to live in.
Wikipedia have articles where I learned from.
This one is general the 51st state article.
51st state - Wikipedia, the free encyclopedia
And this is for the new state from a current state.
List of U.S. state secession proposals - Wikipedia, the free encyclopedia