Vintage Cars: Electrical Grounding, fuse box, car example

Question
How is the electrical system in a car grounded?

Answer
most all cars, especially vintage use a negative ground system.  The electrical loop  /-  uses the frame of the car as the ground.  The negative or black wire connects to the frame at varrious points on the car.  A good ground is essential for correct operation of all of the operating systems of the car.
Example: current from the positive wiring from the positive terminal of the battery, or fuse box, travels to a light bulb. Once the current has passed through the filament of the light bulb, it passes through the housing of the light bulb and grounds to the frame. The negative battery terminal is also grounded to the frame, which causes the frame to serve as a gigantic piece of wire.