What new industry had the most impact on the 1920s?

The automobile industry had the most significant impact on the 1920s, revolutionizing transportation and reshaping American society. The mass production techniques pioneered by companies like Ford made cars more affordable, leading to increased mobility, the growth of suburbs, and the development of related industries such as oil and road construction. This shift not only transformed daily life but also contributed to economic growth and changes in social dynamics during the decade.