The Great Depression and the Dust Bowl
Here Comes that Rainbow Again is a song inspired by a scene in the movie The Grapes of Wrath, based on the book by John Steinbeck. You may very well read this book as an assignment in high school.
The Grapes of Wrath is the story of a family from Oklahoma who leave their family farm due to the dust bowl, and travel to California to look for work. They have many problems, and people are often unkind, but in this scene a waitress at a roadside diner is willing to help.