Final answer:
The most recent AVA in Oregon, as of May 2021, is the Van Duzer Corridor AVA, established in December 2019, and known for its unique climatic influences in the Willamette Valley.
Step-by-step explanation:
As of the information available up to May 2021, the most recent American Viticultural Area (AVA) designated in Oregon is the Van Duzer Corridor AVA, which was established in December 2019. Oregon's wine regions are renowned for their unique climates and soil types, which contribute to the distinct characteristics of their wines. The Van Duzer Corridor AVA is located in the Willamette Valley and is distinguished by its coastal breezes that influence the terroir, offering a cooling effect that is beneficial for the development of Pinot Noir grapes, among others.