In the midst of an extended road trip across the United States, Robert Frank pointed his camera lens at a passing trolley in New Orleans, took a single exposure, and then turned back to bustling Canal Street, where crowds of people swarmed the sidewalks. That single click of the shutter produced a picture with enduring clarity: a row of windows framing the street car’s passengers-white passengers in the front, black passengers in the back.

Frank captured individual faces gazing from each rectangular frame, from the weary black man in his work shirt, to the young white girl just in front of him, her hand resting on the wooden sign that designated areas segregated by race. In 1958, Frank wrote: With these photographs, I have attempted to show a cross-section of the American population. My effort was to express it simply and without confusion. By the time The Americans was published in the United States in 1959 (he managed to publish a French edition the previous year), with this image now appearing on its front cover, New Orleans street cars and buses had been desegregated through a May 30, 1958 court order. But Jim Crow was still in full swing, the 1960s Civil Rights struggles still ahead. An essay by curator Lucy Gallun conveys how this image continues to reverberate in new contexts today.