<p>This is the tallest operating lighthouse in Duluth.  It was completed in 1901.  This lighthouse originally displayed a 4th order fresnel lens and which was rotated by a clockworks mechanism.  That lens has been removed and is now on display in the Canal Park Marine Museum, which is adjacent to the Duluth ship canal.  The lens currently being used is a plastic fresnel lens which is also rotated to produce a flashing white light.
</p><p>The purpose of this light was to help ships align themselves to the canal at night.  If the white flashing range light can be seen directly above the steady green light of the lighthouse at the end of the same pier, then you know you are approaching the canal straight on.  If the two lights are not seen one above the other, then you are not lined up with the canal.
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This lighthouse was sold in 2008 and is now in private hands, but it is still active as an aid-to-navigation.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/9197427@N06">Pete Markham</a> from Loretto, USA
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/pmarkham/7564443158/">Duluth South Pier Inner Range Light</a>