Gateway Casinos Sault Ste. Marie (formerly OLG Casino Sault Ste. Marie) is a casino in Sault Ste. Marie, Ontario. Owned an Operated by Burnaby based Gateway Casinos & Entertainment, it was Northern Ontario's first full-time casino when it opened in 1999. The casino is located near the International Bridge which links the city to Sault Ste. Marie, Michigan.