A Week on the Concord and Merrimack Rivers (1849) is a book by American writer Henry David Thoreau (1817-1862). It recounts his experience on a boat trip with his brother on the Concord River and Merrimack River.

A Week on the Concord and Merrimack Rivers is ostensibly the narrative of a boat trip from Concord, Massachusetts to Concord, New Hampshire, and back, that Thoreau took with his brother John in 1839. John died of tetanus in 1842 and Thoreau wrote the book, in part, as a tribute to his memory. While the book may appear to be a travel journal, broken up into chapters for each day, this is deceptive. The actual trip took two weeks and while given passages are a literal description of the journey - down the Concord River to the Middlesex Canal, to the Merrimack River, and back - much of the text is in the form of digressions by the Harvard-educated author on diverse topics such as religion, poetry, and history. Thoreau relates these topics to his own life experiences, often in the context of the rapid changes taking place in his native New England during the Industrial Revolution, changes that Thoreau often laments.

It received only two reviews. The Athenæum described it as one of the "worst offshoots of Carlyle and Emerson." The Westminster Review also took issue with its style, though in all felt that "the book is an agreeable book." Thoreau had sent a copy to James Anthony Froude, who wrote back, "In your book . . . I see hope for the coming world."

An 1853 short story by Herman Melville, "Cock-A-Doodle-Doo!", is interpreted as a satire of Thoreau's book.

The French composer Robert Piéchaud (born 1969) wrote The River (2016), a wind quintet which freely follows Thoreau's work. An additional voice part is found in the last movement, setting All Things Are Current Found, the last poem of the book.

John McPhee recreated Thoreau's journey in a canoe starting August 31, 2003, and wrote about it in "Paddling After Henry David Thoreau". (wikipedia.org)