[davekc]

They usually go for the closest truck within range. Especially on anything farther out than 100 miles. They aren't going to pay a truck farther out if one is closer that they don't.
Good example in the extreme is if you are on the southern TX board and you are in Corpus at number one, they aren't calling you for a load in Laredo (which is on the same board) if they have a truck there. Even if you ave sat for 24 hours and that truck just pulled in. As Turtle mentioned, it is based on radius from the customer, not board position. The latter is the secondary consideration.
If one is new and unclear where to go, Look at the EM, and then look at something like getloaded. Even though it is cheap freight, it will tell you where much of the freight is being produced. We base our decisions on where the freight is, rather than board positions , maps and the like.
It may be a little different for vans, just because there are so many of them. Don't know?