The decision by United Airlines to stop serving Springfield is expected to lead to higher airfares for travelers flying to Chicago, according to Kerry Tan, an economist specializing in air travel at Loyola University in Maryland. Tan also said that communities the size of Springfield are vulnerable to the loss of air service. United’s departure will leave Springfield served only by two airline routes: American’s flight to and from O’Hare and the discount carrier Allegiant Airlines’ less frequent flights to and from Punta Gorda/Ft. Myers, Florida. American Airlines recently announced it would discontinue its daily flight between Springfield and Dallas-Fort Worth on June 1, when it too will begin offering two flights daily to O’Hare International Airport.