The United States may have been founded on the idea that all men are created equal, but during the late 18th and early 19th centuries, slaveholding was common among the statesmen who served as president. All told, at least 12 chief executives—over a quarter of all American presidents—were slave owners during their lifetimes. Of these, eight held slaves while in office.

Washington standing among African-American field workers harvesting grain. (Credit: Buyenlarge/Getty Images)

The “peculiar institution” loomed large over the first few decades of American presidential history. Not only did slave laborers help build the White House all of the earliest presidents (except for John Adams and his son John Quincy Adams) were slave owners. George Washington kept some 300 bondsmen at his Mount Vernon plantation. Thomas Jefferson—despite once calling slavery an “assemblage of horrors”—owned around 175 servants. James Madison, James Monroe and Andrew Jackson each kept several dozen slaves, and Martin Van Buren owned one during his early career.

William Henry Harrison owned several inherited slaves before becoming president in 1841, while John Tyler and James K. Polk were both slaveholders during their stints in office. Zachary Taylor, who served from 1849-1850, was the last chief executive to keep slaves while living in the White House. He owned some 150 servants on plantations in Kentucky, Mississippi and Louisiana.

Portrait of Isaac Jefferson, slave of Thomas Jefferson circa 1847. (Credit: Fotosearch/Getty Images).

Perhaps surprisingly, the last two presidents to own slaves were both men closely associated with Abraham Lincoln, who led the nation during a civil war caused in large part by the divisions sowed by slavery, and later signed the Emancipation Proclamation and championed passage of the 13th Amendment ending slavery. Andrew Johnson, who served as Lincoln’s vice president before becoming president in 1865, had owned at least half a dozen slaves in his native Tennessee and even lobbied for Lincoln to exclude the state from the Emancipation Proclamation.

The last president to personally own slaves was Ulysses S. Grant, who served two terms between 1869 and 1877. The former commanding general of the Union Army had kept a lone black slave named William Jones in the years before the Civil War, but gave him his freedom in 1859. Grant would later sum up his evolving views on slavery in 1878, when he was quoted as saying that it was “a stain to the Union” that people had once been “bought and sold like cattle.”