Number of First Ladies: 46 (official total, counting Frances Cleveland twice)
Number of living First Ladies: 7 (Betty Ford, Rosalynn Carter, Nancy Reagan, Barbara Bush, Hillary Clinton, Laura Bush, Michelle Obama)
First use of the term "First Lady": 1849 (by Zachary Taylor, at Dolley Madison's funeral)
First Ladies officially counted as First Ladies although they died before their husbands were sworn in: 4 (Martha Skelton Jefferson, Rachel Robards Jackson, Hannah Van Buren, Ellen Arthur)
Official First Ladies who weren't married to the President: 1 (Harriet Lane, niece of the unmarried James Buchanan)
Unofficial First Ladies – nieces, daughters, daughters-in-law, etc – who carried out social duties on account of the death, illness or disposition of the President's wife: 10 (Martha Randolph, Emily Donelson, Sarah Jackson, Angelica Van Buren, Jane Harrison, Priscilla Tyler, Mary McElroy, Rose Cleveland, Mary McKee, Margaret Wilson)
First Ladies who died while First Lady: 3 (Letitia Tyler, Caroline Harrison and Ellen Wilson)
First Ladies who married in the White House: 1 (Frances Folsom Cleveland)
Longest-lived First Lady: Bess Truman (died aged 97 years, 247 days)
Highest-profile pre-Civil War First Lady: Dolley Payne Todd Madison, who entertained lavishly, instituted the inauguration ball, refurbished the White House, rescued many valuables when the British sacked Washington in 1814 but also served occasionally as First Lady for the widowed Thomas Jefferson, when his daughter was unavailable.
Highest-profile post-Civil War First Lady: Jacqueline Lee Bouvier Kennedy, who created such a sensation when she travelled with her husband to Europe that he was reduced to saying: "I am the man who accompanied Jacqueline Kennedy to Paris."
Most sober First Lady: Lucy Ware Webb Hayes, who banned alcohol from the White House, earning herself the nickname Lemonade Lucy.
Least sober First Lady: Betty Bloomer Warren Ford, who went on to found the famous Betty Ford Center for rehabilitation in California.
Most powerful First Lady: Edith Bolling Galt Wilson, who screened all her husband's work while he was convalescing from a stroke and decided which matters were important enough to bring to his attention.
Cleverest First Lady: Lou Henry Hoover, a geologist, Egyptologist and classicist who conversed with her husband in Chinese. (Runner-up: Hillary Clinton.)