Find True North
Unfortunately, magnetic north (where the compass points) is not true north (the North Pole). The difference between the two (called magnetic declination) varies with location and is listed in the map key. Since most maps are oriented toward true north, you must correct your compass bearings to get an accurate direction. To do this, adjust the orienting arrow on your compass to whatever the declination is (for instance, about 14 degrees east in central Colorado). If your orienting arrow isn’t adjustable, make the correction by subtracting east declinations and adding west declinations to true bearings (“East is least; west is best”). For example, if your central Colorado map shows a 90-degree bearing (the true bearing) to reach a hilltop, you’d set your compass to 76 degrees (the magnetic bearing).