Magnetic Declination
August 21, 2017
The angular difference between the geographic and the magnetic meridians at a point on the earth is called magnetic declination. The values for magnetic declination in Wisconsin vary today from -4.0° in Door County to +1.5° in the west-central part of the state. While these values are not as great as the +20° declination in Seattle, Washington, they are still of concern to surveyors, map makers and navigators, and others who use maps or compasses.