More than 2.7 million travelers on 44,000 flights travel across the United States each day – a figure that has increased every year since 2008. According to S&P Global Ratings, nearly 45 percent of all Americans took a commercial flight in 2018 and 42 percent of U.S. citizens now own a passport, compared with just 15 percent in 1997. Demand shows no signs of stopping, with this summer expected to set a record of 10 years of consecutive growth.

Just take a look at the chart below. Domestic air traffic has increased an average of 2.2 percent annually since 2002 – with only two years of declines in 2008 and 2009. Both domestic and international enplaned passengers set a record in 2018 for a total of more than 1 billion flyers.

U.S. airports enplaned more than 1 billion passeners in 2018
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How have carriers and airports kept up with passenger demand?

Carriers have added more capacity. With the exception of JetBlue Airways and Spirit Airlines, capacity, as measured by seats on all domestic carriers, is up from 2018. The big four airlines – United, Delta, American and Southwest – as seen in the chart below, account for more than 81 percent of domestic airline capacity.

Mainline carriers have actually decreased flights while increasing seat capacity. On the other hand, ultra-low cost carriers – such as Allegiant, Frontier and Spirit – have grown the number of flights by 91 percent. In 2013, about 29 percent of the U.S. domestic market was exposed to ultra-low cost carriers. In just five years that figure has expanded to 56 percent in 2018.

share of industry capacity by airline, 2018
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