Ultramar Diamond Shamrock was a large independent refiner operating in the US and Canada that was formed by the merger of the Diamond, Shamrock and Ultramar refining companies, and the acquisition of the North American refining assets of Total.

The company was ultimately acquired by Valero.

Refineries

California

Wilmington (1997 - 2002)

Colorado

Commerce City (1997 - 2002)

Michigan

Alma (1997 - 1999)

Nova Scotia

Dartmouth (1997 - 2002)

Holyrood (1997 - 2002)

Oklahoma

Ardmore (1997 - 2002)

Quebec

Quebec City (1997 - 2002)

Texas

McKee (1997 - 2002)

Three Rivers (1997 - 2002)