During normal operations, what flag is flown at the bow of a US Navy ship in port?

The flag that is flown at the bow of a US Navy ship while in port is the Union Jack. This flag symbolizes the sovereign authority of the United States and is flown by Navy vessels when at anchor or moored. The Union Jack represents the Navy as a branch of the armed forces and serves to signify the presence of the ship in a port, showcasing its active status while allowing other vessels and observers to recognize its identity and honor.

In contrast, the National Ensign is flown at the stern of the ship, the Maritime Signal Flag pertains to communication between ships and is not used for display purposes while stationary in port, and the Admiralty Flag does not apply in this context. Therefore, it is the Union Jack that has the specific role of being displayed at the bow during normal operations in port, making it the correct answer to the question.