An interior rearview mirror system includes a compass system and a display. The compass system is operable to display information indicative of a directional heading of the vehicle to a driver of the vehicle. The display comprises a plurality of ports formed in a reflective coating of a mirror reflective element and includes illumination sources positioned behind and generally aligned with corresponding ones of the ports. Each of the illumination sources may be energized to project illumination through a respective one of the ports such that the ports are backlit by the respective illumination sources, in order to convey the directional information to the driver of the vehicle. The system may include a microprocessor operable to control each illumination source via a respective wire connected between the microprocessor and each illumination source. The compass system may utilize a global positioning system for vehicle direction determination.