In 1959, a seemingly unassuming collection from the Swiss-born photographer Robert Frank appeared in U.S. bookstores. Shot on a series of road trips and coupled with an introduction by Jack Kerouac, the 83 images in The Americans were curious and unsettling, marked by dim lighting, abrupt cropping, and sly camera angles. The impact was revolutionary, offering the country a sobering portrait of itself at a cultural crossroads and photographers a new way to think about their medium. To mark the 50th anniversary of the collection (first released in 1958 in France), German publisher Steidl worked with the 84-year-old Frank to design (even recropping the images) a new edition ($39.95; steidlville.com), on sale now, in time for the National Gallery of Art’s “Looking In: Robert Frank’s The Americans” (opening January 18; nga.gov). The result is as hypnotic and revealing as it was half a century ago.