US domestic aviation market: mature, but new opportunities arising

Despite a certain level of maturity, route development in the US continues to evolve.

The three largest US global network airlines are largely focused on leveraging the strength of their hubs, but Delta Air Lines has also built up a smaller group of focus cities during the past couple of years: in Raleigh/Durham, Cincinnati (a former hub) and Boston, which is a stronghold for JetBlue.

Delta's continued build-up in the market could prove to be a challenge for JetBlue in Boston, which is the airline's largest focus city by departing frequencies (as of late Feb-2019).

In 2019 the US ULCCs Spirit and Frontier are making a push from Delta's Raleigh focus city, after Frontier's market share at the airport reached nearly 6% in 2018. Spirit is also the first US ULCC to enter Charlotte, where American is the dominant airline by a wide margin. American has already responded to Spirit's mild market entry by adding capacity to the markets where Spirit plans to launch services.

None of those developments are earth shattering; but they do reflect a level of posturing that remains in the the US, despite four airlines dominating the market.