Ultramar Diamond Shamrock

Also known as: 

UDS

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.

Refining history

1933 - Shamrock opens McKee refinery

1950 - Shamrock acquires Saginaw, Michigan refinery from Louis Rose

1954 - Shamrock shuts down Saginaw, Michigan refinery

1961 - Ultramar opens Holyrood, Nova Scotia refinery

1967 - Shamrock and Diamond merge to form Diamond Shamrock

1971 - Ultramar opens Quebec City refinery

1983 - Ultramar shuts down Holyrood, Nova Scotia refinery

1984 - Diamond Shamrock acquires Three Rivers refinery from Sigmor

1988 - Ultramar acquires Wilmington refinery from Union Pacific Resources

1990 - Ultramar acquires Dartmouth, Nova Scotia refinery from Texaco

1994 - Ultramar shuts down Dartmouth, Nova Scotia refinery

1997 - Ultramar and Diamond Shamrock merge to form Ultramar Diamond Shamrock

1997 - Ultramar Diamond Shamrock acquires North America refining assets of Total (Commerce City; Ardmore; Alma, Michigan)

1999 - Shuts down Alma, Michigan refinery

2002 - Company acquired by Valero