Williston is a city in North Dakota, USA. The city has very low ratings that never go above 50.
The default airport here is Sloulin Field Int'l Airport (ISN).
Due to its extremely low ratings, it is strongly recommended to not start here. The lack of demand on routes means there are very few viable routes out of WIlliston. Although it's non-existent, the city cannot sustain any form of competition and any such routes should be closed. Although the city is in an advantaged location to make routes to major American cities (Los Angeles, Seattle, etc.) trans-atlantic flights are not recommended as the city does not have the demand to support the routes.
Sloulin Field Int'l Airport is usually empty and will never get upgraded beyond its initial status of Level 1. This makes any additional airports in the city completely worthless. Buying the airport is also strongly not recommended as the meager profits will not be enough to make up for the huge cost in cash or credits.
Due to its size, only small planes such as the Airbus A320 or Boeing 737 are worth using on routes to large cities. Regional jets such as the Bombardier Dash 8 can be used for medium-sized cities. Large and medium planes should never be used as they will be impossible to fill and will result in depreciation.