Newmarket Costco Store in East Gwillimbury helloSeptember 4, 2018 Categories: CrystalAddress 18182 Yonge St.L9N 0J3 East Gwillimbury, Ontario, CanadaContact Contact Store Review Store Your Name * Your Email * ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ Your Review * Find on Map