Cheapest short-haul flights - USA?

Question

Hello, which airlines are the cheapest for inside flights in the USA?

I know about TranAir but what else? and when is the best time to book for a flight if I want the cheapest fare? 1 day before , 1 week before, 2 months before?

Answer 1

http://www.allegiantair.com currently with $29 flights to/from Florida, for example.  Also http://www.spiritair.com sometimes with $9 specials (very limited).  Cheapest 21-90 days advance.  More than 90, and you'll probably miss a good sale.  Less than 21, and you've missed the advance-purchase cutoff for most of the cheapest fares.