My wife is returning from a trip to LGA and I checked her flight (441) on flightaware and was surprised to learn that this 737 uses one flight number for this entire trip:

Rochester, NY (ROC) - Chicago, IL (ORD) - Houston, TX (IAH) - Denver, CO - San Francisco, CA (SFO)

I would expect UA to switch the flight number at IAH (i.e. ROC-ORD-IAH on one flight number and IAH-DEN-SFO on another). Are they short of flight numbers? Why else would you use one number for this entire 3282 mile run?

Can anybody else find a similar mainline UA routing? I know this is more common on UEX flights.