Where does the expression “Black Mario” come from and What does it mean?

The term “Black Mario” is the popular name for a police wagon or van, the vehicle sent from a police station to pick up or transport persons under arrest.

The source of the name is altogether traditional, not known to be fact, but generally accepted.

The name is said to be the familiar sobriquet of a Negress, Maria Lee, who ran a lodging house for sailors in Boston, probably in the early 1800s. She was a woman of huge stature and, it is said, willingly assisted the police whenever her lodgers became unruly or violated the law.

If this story is true, her name must have made a deep impression upon such British subjects as fell afoul of the law when guests at her house, for the appellation “Black Maria” was first applied to a prison van in London.