E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
The black van which conveys prisoners from the police courts to jail. The French call a mud-barge a Marie-salope. The tradition is that the van referred to was so called from Maria Lee, a negress, who kept a sailors boarding house in Boston. She was a woman of such great size and strength that the unruly stood in dread of her, and when constables required help, it was a common thing to send for Black Maria, who soon collared the refractory and led them to the lock-up. So a prison-van was called a Black Maria.