Manhattan
Manhattan is symbolic of Ellie's rich, sheltered, and white world - the world she grew up in and the world she inhabits.
Brooklyn
Brooklyn is symbolic of Jeremiah's life, his community, and space where he and other black people can freely and safely express themselves.
The Star of David Necklace
The Star of David necklace that Ellie gives Miah represents Ellie's love for Miah.
Loving Someone Outside of One's Community
A common motif in the novel is loving someone who is outside of one's community - like Ellie and Miah.
Acceptance
The novel is an allegory for accepting someone outside of one's social or racial class. It is, in other words, an allegory for acceptance.