Abstract: A detachable vehicle-mounted banner assembly is provided, comprising a banner panel defining two opposing and at least semi-rigid surfaces, the surfaces comprising at least a leading edge; a banner mast comprising a base portion and a flanged portion, the flanged portion comprising an angled leading edge and a trailing slot, the trailing slot being configured to selectively engage at least the leading edge; and a base assembly having a first portion configured for attachment to a vehicle and a second portion configured to attachment relative to the base portion. The base portion is elongate and has a base longitudinal axis about which the banner mast and the banner panel pivot; and the flanged portion of the banner mast extends away from the base portion and has a flange longitudinal axis oriented at an acute angle relative to the base longitudinal axis. A method of mounting the assembly is also provided.