"The first modem mass medium, radio made America into a land of listeners, entertaining and educating, angering and delighting, and joining every age and class into a common culture. Radio created national crazes across America, taught Americans new ways to talk and think, and sold them products they
never knew they needed. Radio brought them the world."
-Source: Tom Lewis, historian, "A Godlike Presence': The Impact of Radio on the 1920s and 1930s." 1992
The effects of radio described in the excerpt is most similar to the effects caused by which of the following improvements?