After high school and his compulsory eight months in the Swedish military, Wallenberg's paternal grandfather sent him to study in Paris. He spent one year there, and then, in 1931, he studied architecture at the University of Michigan in the United States. Although the Wallenberg family was rich, he worked at odd jobs in his free time and joined other young male students as a passenger rickshaw handler at Chicago's Century of Progress. He used his vacations to explore the United States, with hitchhiking being his preferred method of travel. About his experiences, he wrote to his grandfather saying, "When you travel like a hobo, everything's different. You have to be on the alert the whole time. You're in close contact with new people every day. Hitchhiking gives you training in diplomacy and tact."