William spent the majority of his youth in St. Louis. His masters hired him out to work on steamboats on the Missouri River, then a major thoroughfare for steamships and the slave trade. His work allowed him to see many new places. In 1833, he and his mother escaped together across the Mississippi River, but they were captured in Illinois. In 1834, Brown made a second escape attempt, successfully slipping away from a steamboat when it docked in Cincinnati, Ohio, a free state.