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| NORTH STAR PORT | WINTER 2025
Since the mid-1970s experimentation with year-round shipping on Lake Superior, it's become common for the
interlake navigation season to extend beyond 300 days for the Port of Duluth-Superior. The more notable trend
is the lengthening of Duluth-Superior's oceangoing navigation season:
1960
200
250
300
1970 1980 1990
1960s:
222.5 days
DAY
S
1970s:
238.5 days
1980s:
250 days
| By Jayson Hron
Seasons Change
CHARTING THE AVERAGE SHIPPING SEASON LENGTH
Winter
Navigation:
Winter
Navigation:
New reasons for an old argument
Leon Fraser, left, and Thomas W. Lamont,
above, were among the hardy sextet of
vessels that sailed for a full calendar year
in the mid-1970s.
PHOTOS / Kathleen Wolleat, University of Wisconsin-Superior Jim Dan Hill Library Historical Archives
