E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Up to the Hub.
Hub is an archaic word for the nave of a wheel, the hilt of a weapon, or the mark aimed at in quoits. If a cart sinks in the mud up to the hub, it can sink no lower; if a man is thrust through with a sword up to the hub, the entire sword has passed through him; and if a quoit strikes the hub, it is not possible to do better. Hence the phrase means fully, entirely, as far as possible. It is not American, but archaic English. (See HUB.)
I shouldnt commune with nobody that didnt believe in election up to the hub.Mrs. Stowe: Dred, vol. i. p. 311.