Efficient and effective route network management has long been seen as the key to success for any airline. Historically, carriers have carefully tracked patterns in supply and demand to best leverage their limited fleets to serve the destinations that will earn them the highest profits. Route management systems have become so effective that today there are extremely few routes with proven demand that are not currently served by legacy carriers. That is to say, if an airline sees that enough passengers are flying to a destination via stopping services, they will likely see the opportunity to begin flying nonstop between the two cities.