Bryant was born on November 3, 1794, in a log cabin near Cummington, Massachusetts; the home of his birth is today marked with a plaque. He was the second son of Peter Bryant, a doctor and later a state legislator, and Sarah Snell. His maternal ancestry traces back to passengers on the Mayflower; his father's, to colonists who arrived about a dozen years later. His paternal father's line goes from Peter, to Phillip, to Icabod and Mr. Stephen Bryant who came to America and married Mehitable Standish the granddaughter of Capt. Myles Standish also of the Mayflower.
Bryant and his family moved to a new home when he was two years old. The William Cullen Bryant Homestead, his boyhood home, is now a museum. After just two years at Williams College, he studied law in Worthington and Bridgewater in Massachusetts, and he was admitted to the bar in 1815. He then began practicing law in nearby Plainfield, walking the seven miles from Cummington every day. On one of these walks, in December 1815, he noticed a single bird flying on the horizon; the sight moved him enough to write "To a Waterfowl".
Bryant developed an interest in poetry early in life. Under his father's tutelage, he emulated Alexander Pope and other Neo-Classic British poets. The Embargo, a savage attack on President Thomas Jefferson published in 1808, reflected Dr. Bryant's Federalist political views. The first edition quickly sold out—partly because of the publicity earned by the poet's young age—and a second, expanded edition, which included Bryant's translation of Classical verse, was printed. The youth wrote little poetry while preparing to enter Williams College as a sophomore, but upon leaving Williams after a single year and then beginning to read law, he regenerated his passion for poetry through encounter with the English pre-Romantics and, particularly, William Wordsworth.
Although "Thanatopsis", his most famous poem, has been said to date from 1811, it is much more probable that Bryant began its composition in 1813, or even later. What is known about its publication is that his father took some pages of verse from his son's desk and submitted them, along with his own work, to the North American Review in 1817. The Review was edited by Edward Tyrrel Channing at the time and, upon receiving it, read the poem to his assistant, who immediately exclaimed, "That was never written on this side of the water!" Someone at the North American joined two of the son's discrete fragments, gave the result the Greek-derived title Thanatopsis (meditation on death), mistakenly attributed it to the father, and published it. With all the errors,[clarification needed] it was well-received, and soon Bryant was publishing poems with some regularity, including "To a Waterfowl" in 1821.
On January 11, 1821, Bryant, still striving to build a legal career, married Frances Fairchild. Soon after, having received an invitation to address the Harvard University Phi Beta Kappa Society at the school's August commencement, Bryant spent months working on "The Ages," a panorama in verse of the history of civilization, culminating in the establishment of the United States. That poem led a collection, entitled Poems, which he arranged to publish on the same trip to Cambridge. For that book, he added sets of lines at the beginning and end of "Thanatopsis." His career as a poet was launched. Even so, it was not until 1832, when an expanded Poems was published in the U.S. and, with the assistance of Washington Irving, in Britain, that he won recognition as America's leading poet.
His poetry has been described as being "of a thoughtful, meditative character, and makes but slight appeal to the mass of readers."