endgate

An American English word for the removable board or hinged panel at the back of a wagon or cart — what British English calls a tailboard. The endgate held the load in and could be dropped or removed for loading and unloading. The term is deeply embedded in American agricultural and frontier history, showing up in accounts of covered wagon travel, farm life, and rural commerce. In modern usage it's largely historical, though it survives in some rural American dialects and old-timey writing about pioneer life.

(US) tailboard.