Significance of flight numbers

[Adeel]

Is there any significance to the way flight numbers are assigned. I'm particularly curious about lower numbered flights. CO 1 for example is IAH-HNL-GUM and CO 2 is the reverse. Does this mean this is CO's "flagship" route? Is there any such significance to lower numbered routes? Does it indicate the age or revenue value of the route for a carrier?

[coachrowsey]

With US, US West flight numbers are below 700. Any number above is US East.