Harriet Rebecca Lane Johnston (May 9, 1830 – July 3, 1903) acted as first lady of the United States during the administration of her uncle, lifelong bachelor president James Buchanan, from 1857 to 1861.

She lost her mother when she was nine; when her father's death two years later made her an orphan, she requested that her favorite uncle, James Buchanan, be appointed as her legal guardian.

Women copied her hair and clothing styles (especially when she lowered the neckline on her inaugural gown by 2.5 inches), parents named their daughters for her, and a popular song ("Listen to the Mockingbird") was dedicated to her.

As sectional tensions increased, she worked out seating arrangements for her weekly formal dinner parties with special care, to give dignitaries their proper precedence and still keep political foes apart.

Seven states had seceded by the time Buchanan retired from office and returned with his niece to his spacious country home, Wheatland, near Lancaster, Pennsylvania.

Her uncle cautioned Lane against "rushing precipitately into matrimonial connections" as his ward found her potential suitors "pleasant but dreadfully troublesome".

[6]At Harriet Lane Johnston's funeral, services were conducted by Bishop Satterlee and Canon DeVries of the Washington National Cathedral.

Lane left bequests in her will that established a children's hospital and a boys' school, and she donated her collection of artwork to the Smithsonian.

[7] She dedicated $400,000 (equivalent to $14,000,000 in 2024) to establish the Harriet Lane Home for Invalid Children at the Johns Hopkins Hospital in Baltimore, Maryland as a memorial to two sons who had died in childhood.

Eventually treating over 60,000 children a year, the Harriet Lane Home became a pioneer treatment, teaching, and research clinic.

From 1930 to 1963 Helen Taussig, who helped to develop the blue baby operation, headed the pediatric cardiac clinic.

Lawson Wilkins established an endocrine clinic that developed procedures used universally to treat children with certain glandular disorders, including dwarfism.

The pediatric medicine Harriet Lane Handbook series continues in print and online, with multiple titles.