North and South Carolina were seperate colonies from the beginning of the 18th century, before American independence. West Virginia was split from Virginia during the American Civil War as free territory.

The split of North and South Carolina was administrative and done mutually during the colonial period, whereas the division of Virginia during the Civil War was not a mutual split — so while the new state was named West Virginia, the old state remained "Virginia" since it hadn't willingly divided itself into East and West.

When Virginia began to discuss secession from the Union, the majority population of the western part of the state was opposed . Militia units began to be raised there, on both sides of the issue, local governments became split, and local governance was in danger of breaking down. To prevent more chaos, an anti-secession politician, John Carlile, proposed a meeting of representatives from all the counties of "Northwestern Virginia" in a preliminary convention in Clarksburg in April 1861, resulting in the First Wheeling Convention in May, which decided to create a new state only if the Virginia legislature in Richmond voted to secede. It did, and so details for a new state were hammered out in other Wheeling conventions over the next three years. There was a constitutional difficulty with this, the creation of a state from another state, and Carlile and others proposed a "Restored State of Virgina", taking the position that the legitimate government of Virginia was the western one, and the east was in revolt..so, in effect, a new state wasn't being created, only the eastern part had left the Union. In theory if this had been pursued there could now be a "Virginia", and an "East Virginia", but eventually the constitutional issues were resolved and West Virginia became a state.

By the way, if you've never been here, there has always been a pretty strong division between the places. Calling someone from West Virginia a Virginian will tend to get a negative reaction. Which is why you sometimes see West By God Virginia.

North Carolina and South Carolina were founded separately. The North Carolina colony was settled by ppl moving south out of Virginia and was called Albemarle before the concept of Carolina came about.

The South Carolina Colony started at Charleston and moved out from there. The king decided to call all the area from the Savannah river to Virginia Carolina (Latin for Charles) even though they had different population locations. Eventually their differences could not be resolved and they separated.

Their separate founding and settlement can be found in the book Conceived in Liberty which is freely available online.

FYI there was an original East and West Jersey but that was resolved.