Upper panels: comparison of the signed values of polar field strengths, obtained from line-of-sight NSO/KP magnetograms, in the latitude ranges, 45°–90°, 55°–90°, and 60°–90° for the northern (top) and southern hemisphere (bottom), for the period February 1975–November 2016, covering solar cycles 21–24. The reversal of polar fields is clearly seen from the zero-crossing of fields around the solar maximum phase of each cycle. Lower panels: blow up portion for cycle 24. The extended zero-field conditions of polar reversal in the northern hemisphere is apparent at all latitude ranges, which is completed only around November 2014 as indicated by a small blue solid line in cycle 24.