Which lines on a map indicate true north with no magnetic variation?

Which lines on a map indicate true north with no magnetic variation?

• A. Agonic Lines
• B. Isogonic Lines
• C. Meridians
• D. Latitudinal Lines

Answer: (A)

An agonic line marks locations where magnetic declination is zero, so true north and magnetic north align. Along this line, a compass points directly toward true north without needing any adjustment for variation. Lines of equal magnetic variation, isogonic lines, indicate where the declination has the same magnitude but isn’t necessarily zero, so some correction would still be needed there. Meridians are lines of longitude governing geographic east–west position, not magnetic variation, and latitudinal lines are parallels of latitude that measure distance north or south from the equator. So the line indicating true north with no magnetic variation is the agonic line.