Complex sentence: In 1988, after graduating from CalArts, she returned to Portland to found ASIFA-Northwest with Marilyn Zornado, the ASIFA chapter in the Northwest region of the United States which comprised Portland, Seattle, Vancouver B.C., and the cities in between.
Split into simpler sentences: In 1988, after graduating from CalArts, Priestley returned to Portland to found ASIFA-Northwest with Marilyn Zornado. This ASIFA chapter included the northwest region of the United States which comprised Portland, Seattle, Vancouver B.C., and the areas in between.