Final answer:
In the early 19th century, American popular music was influenced by societal changes such as the Spanish-American War, reflected in patriotic songs. Popular songs were typically distributed as sheet music. This era was marked by the rise of the first 'pop star'-type stage personalities, industrial growth, and shifts towards a modern, industrialized society.
Step-by-step explanation:
In the early 19th century, U.S. popular music was influenced by a number of social and cultural factors. Before the era of digital music and recordings, popular songs were purchased as sheet music and played on home pianos. The late 19th century, particularly 1898, reflected the sentiments of the Spanish-American War, with patriotic tunes being quite prevalent. Looking at popular music from that time, one might not recognize many songs by name, but themes of patriotism would be noticeable. The collection of songs from 1898 would also show a trend towards a fascination with stage personalities akin to today's pop stars, with figures like Paganini and Liszt being the Elvis Presleys of their age.
Furthermore, the period saw a shift from an agricultural to an industrial economy, which brought changes in society and culture. This also led to a rise in pop culture, including the prevalence of nightclubs and the Jazz Age in the 1920s. The early popular music also captures the essence of America's growth during the Industrial Revolution, with the Transportation Revolution and mass production influencing many aspects of daily life, including entertainment. The music halls, amusement parks, and the burgeoning nightclub scene reflect this dynamic period.