The construction of the poem, with each of the twelve verses starting with the line "Over the river, and through the wood," and the rhyme scheme comprising two verses, abccb, adeed, makes for easy memorization.
The correct title is "The New-England Boy's Song About Thanksgiving Day," which is not easy to remember!
In addition to the Toronto site, the poem also is on line in www.poets -corner.org. or go to the poem at New-England Boy's