What does the term 'city pair' refer to in travel terminology?

The term 'city pair' specifically refers to the two cities that are involved in a journey—one being the place of departure and the other being the destination. In travel terminology, understanding city pairs is crucial as they often determine how routes are planned, the pricing of tickets, and the availability of services between those two locations. Airlines, for example, frequently analyze traffic between city pairs to help guide their route planning and pricing strategies. This concept is fundamental within the travel industry for both the planning of trips and the operational strategies of transportation companies.

The other options, while they relate to travel, do not accurately encapsulate the meaning of 'city pair.' Traveling between two states involves geographical boundaries but does not highlight the specific relationship between two cities. The concept of main airports focuses on air travel hubs rather than on the relationship between cities. Finally, itineraries encompass a broader range of travel planning and may include multiple city pairs, therefore not fitting the precise definition of the term.