The Del Norte County Regional Airport (subtitled, on their website at least, with "At Jack McNamara Field") is an airport with regularly scheduled passenger service, located in Crescent City, California. Its FAA and IATA codes are CEC. The airport is owned by Del Norte County and currently has one scheduled commercial flight a day, subsidized through the Essential Air Service program, flying to Oakland International Airport in Oakland, California. In 2019, the year before the Covid-19 pandemic, it carried a little over 9000 passengers a year, and in 2020, this decreased to around 4,000 passengers.
While I talked about Essential Air Service on its own, I want to talk about this airport as a specific example. Del Norte County has around 28,000 people, and adjoining Curry County in Oregon has around 22,000 people. There are about 50,000 potential customers for this airport. The two nearest large metropolitan areas are Portland, Oregon, around six hours to the north, and San Francisco, six hours to the south. The nearest small metro area is the Medford-Grants Pass area, two hour to the northeast, which is also the center of the nearest non-subsidized commercial airport. There is currently no public ground transportation in and out of Crescent City. Without this airport, travelling out of the region, while not being impossible, would be infeasible for many people. In addition, the airport has life flight service, and is also used for natural resource management (that is, wildland fire fighting) and while it is not normally a Coast Guard air base (those are in North Bend, Oregon and Arcata, California), it might be necessary for law enforcement and military reasons, as well. In other words, this airport needs to keep running for other reasons, so it makes sense to also give the people of the area some sort of air transport to the rest of the country. That is either common sense or a sunk cost fallacy, depending on your viewpoint.
While I can see both the benefits and costs of keeping an airport running in an isolated location, I still find it curious how much prestige air travel has in relation to other forms of travel. The previous private and public transportation routes that went north/south along US Highway 101 are now fragmentary, as are the routes eastward, to Medford and I-5. At the same time, a large new terminal was built for this airport in 2019, even though even before the pandemic, the airport saw roughly two dozen passengers a day. In many places in the United States, especially in rural areas, it is not the question of whether subsidies will exist, but what exactly their purpose is, and how efficiently they accomplish that purpose.
https://www.flycrescentcity.com/