City on the Nile … or a punny end to the joke "When a tight-knit group of cygnets votes, they vote ___"

ASWAN

Think of an Egyptian city that sounds like how a flock of swans might cast their ballots.

This clue has two parts: first, it directly names "Aswan," a famous Egyptian city on the Nile River. The second half plays with the word "as one" (how a unified group votes) but swaps it with "aswan" to fit the joke about cygnets (baby swans) voting together. The pun hinges on the similar sound of "as one" and "Aswan," making the answer a clever twist on both geography and wordplay.