Most of Train's career as an adult was spent in various businesses, particularly as a merchant but also a newspaper owner and financier. He also invested in various forms of transportation in the United States, Australia, and England. Increasingly, he became known as an eccentric; such thoughts likely reached a peak when, in 1870, newspapers scrambled to cover his second trip across the globe — a trip which took about 80 days. His efforts likely inspired Jules Verne in the creation of Phileas Fogg in his 'Round the World in Eighty Days (no one advocated the connection as well as Train himself). Taking advantage of his popularity, he ran for President as an independent candidate in 1872.
In addition to his inspiration to a literary classic, Train was also a writer himself. Towards the end of his life, in 1901, he wrote his autobiography under the title My Life in Many States and in Foreign Lands. The book reflected his further descent into eccentricity (friends suggested he needed to be institutionalized) and was dedicated: "To the children and to the children's children in this and in all lands who love and believe in my because they know I love and believe in them." In his preface, he quoted himself from one of his speeches while campaigning for President:
Many persons attribute to me simply an impulsiveness, and an impressibility, as if I were some erratic comet, rushing madly through space, emitting coruscations of fancifully colored sparks, without system, rule, or definite object. This is a popular error. I claim to be a close analytical observer of passing events, applying the crucible of Truth to every new matter or subject presented to my mind or my senses.