One of his most recognizable works is The Song of Hiawatha, based on an accumulation of American Indian stories and legends. Much of this work was based on The Myth of Hiawatha compiled by Jane and Henry Rowe Schoolcraft. Henry was a historian, explorer, and geologist who was superintendent of Indian affairs for Michigan from 1836 to 1841. Jane was an Ojibway indian whose name translated into english as 'The Woman of the Sound Which the Stars Make Rushing Through the Sky'. The Ojibway, and northwestern Michigan, would serve most of a century later as the background for Ernest Hemingway's Nick Adams stories (a character who bears several parallels to Hiawatha).
Longfellow spent nearly a year and a half on Hiawatha, finishing in November of 1855. The meter he used was based on a Finnish epic poem called the Kalevala. To truely appreciate the measured sound of it, I recommend listening to Maddy Prior's vocals on the second movement of Mike Oldfield's recording Incantations. Oldfield interrestingly uses Ben Jonson's Hymn to Diana in the fourth movement to maintain a similar theme, rythm, and feel.
As an additional item on Longfellow's resume of American Indian works, all of the translated Ojibwa Indian songs in the 'Traditional' section of Poets' Corner are adaptations by Longfellow.
On a personal note, the feel that you get looking out over Lakes Michigan and Superior, or hiking or canoeing through the national forests in Michigan is very consistent with Longfellow's imagery.
This Web version of The Song of Hiawatha was scripted by Steve S. from an existing ASCII text. The vocabulary, I believe, was created by Woodrow W. Morris