After his defeat by Andrew Jackson in 1828, John Quincy Adams refused to attend the victor's inauguration, just as his father had boycotted Thomas Jefferson's in 1801. He wrote in his diary that "The sun of my political life set in the deepest gloom." Filled with sadness for the nation, Adams stayed in Washington for a few months before returning to his hometown of Quincy, Massachusetts. Deeply bored by retirement and still hoping to be politically engaged, the former President promptly agreed—over his family's objections—when neighbors asked him to run for Congress from his Massachusetts district. He set two conditions, however: he would never solicit their votes and he would follow his conscience at all times. His election was one of the greatest satisfactions in Adams's life.

Antislavery Congressional Career

Adams served nine post-presidential terms in Congress from 1830 until his death in 1848, usually voting in the minority. He supported the rechartering of the Bank of the United States, opposed the annexation of Texas and the war with Mexico, and struggled for eight years to end the House's notorious "gag rule," which tabled without debate any petition critical of slavery. Adams attempted to read into the record at every opportunity the hundreds of antislavery petitions that abolitionists around the country sent him on a regular basis. The House finally relented and repealed the rule in 1844.

As one of the House's most articulate and forceful spokesmen against slavery, Adams earned the nickname of "Old Man Eloquent." Whenever he rose to speak, especially in his twilight years, silence swept over the chamber as congressmen turned their attention to the former President. In 1841, Adams argued successfully before the U.S. Supreme Court to win freedom for slave mutineers aboard the Spanish ship Amistad. The Africans had mutinied against their Spanish captors on the high seas and were then captured by an American warship off Long Island. The court ruled that the mutineers were free men because international slave trade was illegal under British and U.S. law.

Keeping in character with Adams's devotion to education and the sciences, he championed the bequest of James Smithson of England, who willed $500,000 to the United States for the creation of an institution dedicated to knowledge—later called the Smithsonian Institution. At the age of seventy-six, in 1843, Adams also traveled to Cincinnati to officiate at the laying of the cornerstone of the Cincinnati Observatory.

On February 21, 1848, a severe stroke hit John Quincy Adams just minutes after he cast a loud vote in opposition to a motion to decorate certain Army officers serving in the Mexican War. It happened on the House floor in the U.S. Capitol Building in Washington, D.C. Two days later, he slipped into a coma moments after reputedly uttering a final sentiment: "This is the end of earth, but I am content." On February 23, 1848, at the age of eighty, the former President died. For two days, mourners filed by his open casket in a House committee room. His body was ultimately interred next to his parents, John and Abigail Adams, beneath the First Congregational Church in Quincy. The man whom many historians consider the most learned person ever to have served as President left his 8,500-volume library and personal papers, as well as his home and lands, to his only surviving son, Charles Francis Adams. He divided the remainder of his estate between his wife, daughter-in-law Mary Catherine Hellen Adams (widow of his second son John Adams II), and granddaughter Mary Louisa Adams.