Viewers in Mississippi await marchers heading to the nation’s capital in the 1968 Poor People’s Campaign. Planning this campaign for economic justice was Martin Luther King Jr.’s final proje …

Viewers in Mississippi await marchers heading to the nation’s capital in the 1968 Poor People’s Campaign. Planning this campaign for economic justice was Martin Luther King Jr.’s final project; he had been assassinated a month before it began. (Ted Polumbaum/Newseum)