A decade of practice and experimentation as a printmaker culminated in a suite of ten color prints made in 1890-91. Combining glaze-like, layered tones of aquatint with the textured surfaces of softground etching and the pure, clear outline of drypoint, Cassatt's innovative prints astonished and amazed her contemporaries. Camille Pissarro, himself a printmaker as well as a painter, admired the perfection of her prints, describing the colors as "subtle, delicate, adorable blues, fresh rose, etc." The result for him was "admirable, as beautiful as Japanese work."
In the Omnibus is the only scene in the series that does not have an interior setting. The theme of travel was appealing to artists in 19th-century Paris-it represented a public space where people of different classes and genders were juxtaposed in close proximity. A quintessential modern life subject, Cassatt depicts a bourgeois lady accompanied by her baby and a nursemaid doing errands in the city. While the nanny and the child interact, the mother's gaze is directed elsewhere, wandering to the world beyond.