What is a notable characteristic of essential air service airports?

Essential Air Service (EAS) airports are characterized by their role as critical regional air service providers, often catering to communities that might not otherwise have sufficient access to air transportation due to their remote locations. The term "Through" airport refers to facilities that provide connectivity between various destinations, typically acting as a link in a broader transportation network.

In the case of EAS, these airports might not handle a large volume of passenger traffic compared to larger hubs but are essential for ensuring that smaller or more isolated communities receive the air service necessary for economic and social connectivity. Being classified as "Through" airports means they are part of a system that includes multiple stops and connections, which is crucial for these smaller markets that rely on federal support to maintain airline service.

In contrast, other characteristics such as primarily supporting international flights or being situated in urban areas do not apply to EAS airports, as they tend to focus on domestic routes to and from less populated regions. Additionally, in many cases, EAS airports do not support a substantial number of transfer passengers, since they primarily serve local or regional demand rather than acting as major connecting points for larger networks.