They started using billboards i believe hope that helps
Explanation:
Primary sources are evidence about what happen in that time, the person's evidence is primary because that person was there.
Secondary are like when somebody tells you something that he heard but he wasn't there.
The Roaring Twenties is the term used to describe the <span>great prosperity in the society and culture during the 1920s</span><span> in the Western world. The period was attributed to economic prosperity especially in the countries : United States, Canada and most nations in the Western Europe. This era marks the emergence of the use of technology such as telephones, films and motion pictures, refrigeration, electricity and many more.</span>