In what cities do the majority of ISS sightings occur?

Because the International Space Station constantly moves throughout the night sky, no specific city can see the station more often than any other. However, NASA's Spot the Station service lets a user input a city to determine times of ISS visibility there.

Spot the Station provides information for over 6,700 cities worldwide, including most major U.S. and international cities. According to NASA, even if the tool does not list a specific city, the viewing opportunities for a nearby city should apply. Each future viewing opportunity includes the date, time, length of visibility, the maximum height of the ISS in the sky, and the latitudes where the ISS appears and disappears beyond the horizon.