United Airlines will boost frequency between Chicago O'Hare and San Juan to daily from 5 November, two weeks before JetBlue Airways is slated to enter the market.
The Chicago-based carrier will offer one daily flight on a 167-seat Boeing 737-900 on the route. It currently offers twice-weekly service aboard a 120-seat Airbus A319, according to Innovata schedules.
"San Juan has been one of United's most popular Caribbean destinations for more than two decades," says Millie Uriarte, director of Latin America onshore and Caribbean sales at United, in a statement. "We are very pleased to increase travel options for business travellers, vacationers and families between Chicago and San Juan."
New York-based JetBlue announced on 4 March that it would launch a daily flight between Chicago and San Juan aboard a 150-seat Airbus A320 from 20 November. It has a focus city in San Juan.
United operates a large hub at O'Hare.
American also flies nonstop on the route, according to Innovata.