What does Papi's baseball hat symbolize in the novel, American Dirt?

Papi's baseball hat symbolizes Luca and Lydia's grief, a grief that must be held in abeyance until they find safety. It also serves as a form of security for Luca, and he relishes the fact that it has his father's distinctive scent. At times he hides behind the brim as they travel and ultimately when they arrive safely in the United States Papi's hat has "taken on a museum like quality" as he treasures it along with the memories of his father (374).