The poster commented that the 'cheap' seats were sold out.
I am not certain if this means 'economy' seats or 'discounted economy' seats. What is 'cheap' to one person is not cheap to another!
THIS is the question .....
While it appear that the 'cheapest' L fare of $1220 ORD-DEL roundtrip IS gone, there are K fare at $1620 and H fare at $1820 and B fare at 2437. I guess I would agree that YES the cheapest fare is gone, but there ARE discount fares available on this route on this day.
Seat map .. on the other hand .. looks very very full.
But the original poster asked about cheap fares being sold out..