Harriet Tubman's signed hymnal. Courtesy of the National Museum of African American History and Culture hide caption

itoggle caption Courtesy of the National Museum of African American History and Culture

Angered by Arizona's crackdown on illegal immigrants, thousands of marchers rallied at Los Angeles City Hall during a May Day march to urge immigration reform. Krista Kennell/Sipa via AP Images hide caption

itoggle caption Krista Kennell/Sipa via AP Images