With numerous cities having airline service downgraded from mainline to RJ, what is the future of GRR? Will UAL downgrade from A320/737 to CRJ's? Right now, NWA, UAL, and Delta have mainline flights into GRR. At one time, GRR had mainline service from USAirways,TWA,Midwest Express, and American, Delta (went from mainline/turboprop to all RJ back to mainline/RJ). JetBlue will be announcing GRR service in the next couple years.