Immediately after graduating from Berkeley, Goldberg secured a position as an engineer with the City of San Francisco's water and sewer department. Though it was a stable job, Rube found it unfulfilling and longed to pursue his artistic aspirations.

Within a year, Goldberg left his engineering post and joined the San Francisco Chronicle as a sports cartoonist. This represented a major shift and a commitment to his passion. This role allowed him to hone his drawing skills and develop his comedic timing.

Seeking broader opportunities, Goldberg moved to New York City and began working for the Evening Mail. This relocation was pivotal, as it introduced his work to a national audience and established him as a rising star in the world of cartooning.

During the early 1910s, Goldberg's distinct style began to emerge. He started drawing his now-famous comical inventions, intricate and absurd machines designed to perform simple tasks in the most convoluted ways possible. These drawings quickly gained popularity.

Goldberg's cartoons became increasingly popular, leading to syndication across the United States. This marked a significant milestone in his career, solidifying his position as a prominent and influential cartoonist with a national following.