Kids Touching, 1940s. (Joe Schwartz/Courtesy of the Smithsonian National Museum of African American History and Culture)

Manitoba James and his children Myrtha, Edna and Mauranee, 1919-25. (John Johnson, Douglas Keister/Courtesy of the Smithsonian National Museum of African American History and Culture)

Twins at WDIA, Memphis, Tenn. in 1948. (Ernest C. Withers Trust/Courtesy of the Smithsonian National Museum of African American History and Culture)

A young girl at a Baltimore City Hall rally, May 3, 2015. (Devin Allen/Courtesy of the Smithsonian National Museum of African American History and Culture)