The Maine section of the IAT/SIA is 138.4 miles (223 kms.) long. The route passes through boreal forests and follows trails, old logging roads, an abandoned railroad bed, and rural public roads to the potato fields of Aroostook County. Beyond Fort Fairfield, the trail enters New Brunswick.

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The members of the International Appalachian Trail acknowledge a chronicle of geoscience investigators who over many decades of mapping and research contributed to the development of the theory of Plate Tectonics and successfully applied it to the Appalachian terranes, thereby establishing the foundation for the IAT.