The "Longest" Islands in the United States

Whidbey Island in Washington state is always calling itself the "longest island in the United States", or "the longest island in the continental United States", or, sometimes, "the longest saltwater-surrounded island in the continental United States". This phrase and its variations are so often repeated that most Washingtonians repeat it as if it were gospel.

However, these claims are totally unsupportable, as the following table shows. It shows all islands in the U.S. over 40 miles long. Length is a subjective concept, and the lengths given are approximate. If an island is long, narrow, and straight, length is easy to determine. For rounded islands, the longest possible distance between opposite shores was used. For bent or crooked islands, like Whidbey, length was calculated by drawing a bent line along the island's main axis from end to end. Thus, Whidbey's length in the following chart could be considered a liberal estimate, since a straight line across it would result in a lower number.

Long Island and Whidbey Island

21 of the 29 islands on the following chart are in Alaska, and 3 more are in Hawaii. Technically, Alaska actually is "continental", but even if the more correct term "contiguous United States" is used to describe the "lower 48", Whidbey Island still ranks only 5th in length. Adding "surrounded by saltwater" to the criteria only excludes Isle Royale. If hurricanes were to chop up Padre and Hatteras Islands by cutting channels through their narrow, sandy widths, that would still leave Long Island, almost three times longer than Whidbey, at the top of the chart.

No reasonable condition can be applied to the process that would eliminate Long Island but not Whidbey. Both are connected by bridges to the mainland, and Deception Pass is just as narrow and salty as the East River. It is true that there are two bridges connecting Long Island to the mainland, and that the only bridge connecting Whidbey first passes over another island, Fidalgo. However, that is counterbalanced by Long Island being far more out into the ocean than Whidbey Island, trapped far inland in Puget Sound. Long Island Sound is far wider than Possesion Sound, too.

One superlative remains: Whidbey Island is indeed the longest island on the Pacific coast of the contiguous United States. This is mainly due to lack of competition from the almost island-free coasts of California and Oregon, though.

RankIslandStateLength (mi)Group or Body of Water
1.Prince of WalesAlaska130Alexander Arch.
2.LongNew York118Atlantic Ocean
3.BaranofAlaska102Alexander Arch.
4.St. LawrenceAlaska100Bering Sea
5.KodiakAlaska98Gulf of Alaska
5.AdmiraltyAlaska98Alexander Arch.
7.Big IslandHawaii94Hawaii
8.UnalaskaAlaska81Aleutian Is.
9.UnimakAlaska78Aleutian Is.
10.ChichagofAlaska74Alexander Arch.
10.PadreTexas74Gulf of Mexico
12.UmnakAlaska72Aleutian Is.
13.NunivakAlaska68Bering Sea
14.AtkaAlaska62Aleutian Is.
15.KuiuAlaska58Alexander Arch.
16.KupreanofAlaska54Alexander Arch.
17.RevillagigedoAlaska53Alexander Arch.
18.HatterasNorth Carolina51Atlantic Ocean
18.MontagueAlaska51Gulf of Alaska
21.AgligadakAlaska46Aleutian Is.
22.AfognakAlaska45Gulf of Alaska
22.Isle RoyaleMichigan45Lake Superior
25.AmchitkaAlaska42Aleutian Is.
26.AttuAlaska41Aleutian Is.
26.WhidbeyWashington41Puget Sound
28.DallAlaska40Alexander Arch.
28.MitkofAlaska40Alexander Arch.

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