The most recent refinery built in the United States is the Texas International Terminals refinery in Channelview, Texas. It started operation in February of 2022.
Refineries are often upgraded or expanded. Depending on how you're thinking about it, older refinieries that are upgraded could be considered "new". For example in 2015 Valero expanded its Corpus Christi refinery that was built in 1975 from 15,000 barrels per day to 290,000 barrels per day.