Why are there Magnetic Compass Zones?
The horizontal and vertical components of the earth’s magnetic field vary considerably at different locations on the Earth. To get an accurate reading from a compass, the compass needle needs to be “balanced”, so it does not drag on the top or bottom of the compass capsule. Because of the variations of the earth’s magnetic field, a compass needle that “balances” perfectly in North America will drag or stick in South America. To accommodate these magnetic variances, the compass industry has divided the earth into 5 “zones”.
