Ma tried to look back, but the body of the load cut off her view. She straightened her head and peered straight ahead along the dirt road. And a great weariness was in her eyes.
– John Steinbeck
The Grapes of Wrath, Chapter 10. The die is now cast as Ma Joad tries to look back at Uncle John’s house, but her view of obscured by the loaded-up truck. So she sets her sights on the road and the future ahead. But she feels "great weariness," suggesting that she may be more worried than she is letting on and foreshadowing that things may not be great in California either.