Fewer airport pairs have scheduled service than in the early nineties, even though smaller carriers were added to the data in the early two-thousands. Part of the step up at that point is the wider coverage.
What this shows: The chart covers 1990 to 2024. It plots Directional origin-destination pairs and Unique markets on a vertical axis of Number of routes. Latest values: Directional origin-destination pairs 13,110; Unique markets 7,573. Data run through 2024.
Conditions and method
A directional origin-destination pair is an ordered airport pair that had scheduled domestic passenger service in at least one quarter of the year, so one airport to a second and the second back to the first are two pairs. A unique market counts each airport pair once whichever the direction, so those two are one market. In 2024 that is 13,110 directional pairs and 7,573 markets. Both count airport pairs with service, not flights or frequencies.
From 2002 Q4 the data cover more of the network, because a federal reporting rule added the smaller airlines to them. Between 2001 and 2002, directional pairs go from 11,347 to 13,618 and unique markets from 6,947 to 8,075. There is a step in directional pairs and unique markets across that year. Part of each of those steps is the wider coverage, and the series cannot separate it from a change in the network. A step is a change larger than all but 5% of the series’ other year-to-year changes.