At the age of seventeen, Heenan crossed the continent to California, which had become a lawless and chaotic place following the 1849 gold rush. There is no detailed record of what he did there, but the New York Clipper reports he was a local celebrity as a powerful boxer, and had proved uniformly successful in fights in private bar rooms. During his time in California he was also known to have spent some time in the workshop of the Pacific Mail Steamship Company in Benicia, which served as state capital in 1853–54.