I have to admit, that is something I've been curious about too. I started on a "spare time" project of downloading WN's schedules in PDF format, then saving them in text format. I wrote a program to then extract the non-stop flights from the text. That has some challenges because when there are 8 entries in the "from" column and 10 in the "to" column, a PDF --> Text save puts the right column into the left column. I have that mostly figured out, but still have a couple of minor issues to work out. A way to read directly from the PDF file would be helpful.

My thought was to next use a program to piece together the flights. So if a plane goes BUR-LAS-DEN and that flight number terminates in DEN, then changes flight numbers and goes on to ABQ, I could put that together, based on the turn time.

Its pretty challenging, however, because the flight schedule changes quite frequently. There are 12 schedules just between March 8 and July 6. Also, even within a flight schedule, things go different on Saturday than they do the rest of the week (and there are other variations throughout the week).