Read the following passage and determine the author's use of symbolism.

As Sofia crossed the border out of North Dakota, she knew what to do. She calmly pulled the car over and parked. Beside her, the sign on the road read Welcome to Montana. Sofia had no intention of ever coming back to this place; there were too many bad memories. She reached into the back seat and opened the bird cage. It was time for Henry to move on as well. His wounds were healed. Henry hesitated a bit on Sofia’s arm. When he finally flew away, he never looked back.

What does Montana symbolize in this passage?