Bonus cities are cities that you have flown less than 10% of your flights to. Any flight you take to a bonus city will be guaranteed to be at least 1/3 full with passengers. A bonus city does not affect cargo.
A bonus city will show on the Routes screen with a green perecentage next to the city name. If no perecentage is visible next to a city, you have already flown more than 10% of all of your flights to that city and it is not a bonus city.
You can also view your bonus cities on the My City Statistics page. This page will show you how many flights you have flown to every city and the percentage of your flights have been flown to a particular city.
Itzamna 03:23, 17 April 2008 (UTC)