1999
- Started up PVC resin plant in Suzhou, China in joint venture with Norsk Hydro
1998
- Started up new linear polyethylene plant in Lake Charles, LA
1997
- Acquired CA&O and ethylene plants in Calvert City, KY
- Started up new Ethylene plant in Lake Charles, LA
1996
- Began first PVC fence production in Booneville, MS
1994
- Acquired Engineered Profiles PVC window plant in Calgary, AB
1993
- Started up additional LDPE line in Lake Charles, LA
- Acquired PVC pipe plant in Wichita Falls, TX
1992
- Started 350 million pound Styrene Monomer plant in Lake Charles, LA
- Acquired PVC pipe plants
- Suzhou Huasu Plastics started as Westlake's entry into China
1991
- Started 1.0 billion pound Ethylene plant in Lake Charles, LA
- Acquired PVC plant in Calvert City, KY
1990
- Acquired 1.0 billion pound Vinyl Chloride Monomer (VCM) plant in Calvert City, KY