In the spring of 1970, Holdt set off to Canada where he had been invited to work on a farm. From here he planned to hitchhike to Chile where he intended to support Salvador Allende’s democratic struggle for social justice. But on his way through the United States, he was held up at gunpoint by young blacks and instead quickly got involved in the black struggle for the next four years. Arriving with only $40 in his pocket, Holdt was shocked and fascinated by the social differences he encountered. He ended up staying in the USA more than five years, criss-crossing the country by hitchhiking more than 100,000 miles and making photographs. He sold blood plasma twice a week to buy film. He stayed in more than 400 homes – from the poorest migrant workers to America's wealthiest families (for instance, the Rockefellers) - recording these encounters on over 15,000 photographs taken with a cheap pocket camera. He would live with people who were so hungry they ate cat food and dirt, often in rat-infested shacks. His work captured the daily struggle of the American underclass and contrasts it with images of the life of America's elite. Upon returning to Denmark in 1976, Holdt began lecturing on social differences in the United States and published a book: American Pictures. He later presented his slideshow at over 300 college campuses across the United States.