In 1953, Frank returned to New York City. He applied for a Guggenheim Fellowship, and submitted a proposal to travel across the United States with his Leica camera. In his application, he wrote: 'It is fair to assume that when an observant American travels abroad his eye will see freshly; and that the reverse may be true when a European eye looks at the United States. I speak of the things that are there, anywhere and everywhere - easily found, not easily selected and interpreted.'

Frank set off in 1955 and spent more than two years on the project, much of that time on the road. For long stretches, he was joined by Mary, Pablo and their young daughter Andrea, who was born in 1954. As his proposal suggested, Frank travelled America as an outsider. He later recalled trying to order apple pie in a café in Texas, where the waitress studiously ignored this bohemian foreigner. In Little Rock, Arkansas, he was arrested and questioned by the local police, who were convinced he was a spy.

Out of 28,000 photographs, he selected 83 to be published in his book The Americans. The original edition, published in France, included a selection of quotations by notable writers that underlined Frank's sharp observations of racial and social divisions in the United States. The American edition, introduced by the beat novelist Jack Kerouac, was greeted with extremely hostile reviews. Critics rejected the snapshot spontaneity of Frank's photographs, and their disenchanted view of America. However, the deliberately grainy quality, apparently casual compositions and highly personal, observational style of Frank's images have established The Americans as perhaps the most influential photography book of the last 50 years.

Many powerful photographs could not be accommodated within the precisely-ordered structure of the book. Most of the photographs in this room are selected from the many additional images that were unpublished at the time. Themes of isolation and loneliness emerge, as Frank captures his subjects sitting alone in a California diner, slumped at a desk, or hemmed in by the rows of tacky goods in a New York drug store.