Unlike many international airlines, most of domestic airlines have a generous mileage expiration policy. In the recent years many (but not all) of domestic airlines switched from their award charts to dynamic pricing but silver lining is that by doing so they updated their mileage programs so that miles no longer expire.
In this article, we put together a list of domestic airlines, and major facts about their programs such as alliance attribution, miles expiration policy and easy ways of earning more miles or extending them if they expire.