The system, run by computer, is attached to the starting gun with a cable. Munising and River Rouge. The film costs a lot of money these days. Accutrack systems are still used by Michigan, Central Michigan, Grand Valley and Hillsdale. I don't know of any high schools in the state that still use one.
Video timing is the cheapest form of automatic timing.
Not any video camera will work. With this, a sensor picks up the flash of the gun from a distance. That starts the clock. A videotape is made of the race finish, and the finish times are recorded on the tape. Not the greatest, but it does the job.