Just because they're trade jobs doesn't mean they're located in "90% of the rest of the country." All the good paying construction trades are going to be in places where they're building lots of high rises; places where rent is high enough to warrant such construction. If you're living in San Francisco as an ironworker then $55,000 means you're barely getting by. Construction jobs tend to start really early in the morning so long commutes are pretty much off the table, too.