Conversation so far:
which state was not officially a state at the beginning of the civil war
The border states during the Civil War were the slave states that didn't leave the Union, including Delaware, Kentucky, Maryland, Missouri, and West Virginia.
was tennessee a border state
Though Tennessee had officially seceded and West Tennessee and Middle Tennessee had voted overwhelmingly in favor of joining the Confederacy, East Tennessee in contrast was strongly pro-Union.
why was the term border states used for delaware, kentucky, maryland, missouri, and west virginia
The term “border state” was used because free states bordered the states to the north.

Question: when does the term date back to
Self-contained rewrite: when does the term border states date back to