The symbol of the captain is a popular one, and poets often use it throughout history. Because sailing has been a staple of humanity in most cultures, people have consistently seen the leadership of a crew on a ship as honorable and something to revere. A captain is a leader and someone who holds the lives of the crew in their hands. Additionally, a captain is responsible for the ship itself, so the captain must possess great moral character, dedication, fearlessness, and bravery. Lincoln enjoyed all these characteristics and his leadership throughout the Civil War resulted in historians viewing him as one of the greatest leaders in human history.

Whitman sees Lincoln as the ideal leader, which makes his loss that much more heartbreaking. When a crew loses a great captain, the crew is left feeling directionless, but Whitman is sure to remind the reader that this captain did all he could to save his ship before he died.

In a general sense, the ship can represent any sort of group of people or movement. However, in a specific sense, the ship in the poem represents America. Just as a ship embarks on a dangerous and uncertain journey, America entered the Civil War that had the potential to destroy the country.