Summerside, port town and seat of Prince County, in the province of Prince Edward Island, Canada. Summerside is situated on Northumberland Strait, 54 km (34 mi) west of the town of Charlottetown and 194 km (121 mi) north of the city of Halifax, Nova Scotia. The Canadian National Railways maintains a ferry service from nearby Port Borden to Cape Tormentine in New Brunswick. Summerside is a tourist resort and trading center. It was incorporated in 1877. Population 7,474 (1991); 14,525 (1996).