Sheet music began to have cars on the cover almost as soon as the automobile was invented. Some songs, like The Swagger Two-Step, didn’t have lyrics, and so the car on the front, along with the opulently dressed couple, seem to have been part of the illustrator’s attempt to make the tune symbolize wealth and class privilege…. Despite the fact that there were only about 8,000 cars in the United States at the time, the illustrator made the automobile more visually prominent than the trolley, perhaps to suggest that the song was modern and urbane. —Cars! Cars! Cars! (Smithsonian Institute)

Thanks for the suggestion, Rosemary.