b. Development of a shared national identity.
The mass production of automobiles, radios, and motion pictures all contributed to the creation of a shared national identity in the United States. Automobiles allowed people to travel more freely and connect with others from different parts of the country. Radios provided a way for people to access news and entertainment from across the nation, and motion pictures helped to create a shared culture and mythology. All of these developments helped to break down regional differences and reinforce a sense of national identity.