The Unsent Letter Mailbox is a pop-up art installation by Sofia Calvin in New York City, designed to combat feelings of isolation by allowing people to write letters that will never be sent. Participants, including a diverse range of individuals from different socio-economic backgrounds, write personal messages, confessions, and hopes for the future. This initiative connects strangers through shared human experiences and emotions, such as regret, love, and hope. The act of writing and reading these letters evokes unexpected emotions and empathy among participants, highlighting commonalities despite different life circumstances.