I have a comprehensive list somewhere, but here's the idea:
http://www.brisnet.com/affiliate/HTML/453frame.html
That's the race of the day for Suffolk. Now if you change the number 453 to other things, it's different tracks. For example, 487 is Fair Grounds, 485 is Gulfstream, etc.
I know Lone Star is one of the tracks, but can't find my list. I know that when I found this, I punched in every number from 350 to 550, and only numbers in the 400's work. I can update this later, but that should get you going.