The town of Portland, Oregon does have most of a Pliocene-Pleistocene volcanic field within its metropolitan boundaries. The Boring Volcanic Field consists of more than 80 cinder cones and small shield volcanoes. The youngest volcano (Beacon Rock) in the Volcanic Field erupted about 57,000 years ago.
Since activity began in this area 2.6 million years ago, it is rare for 50,000 years to pass without an eruption. However, all existing Boring Volcanic centers are extinct and the probability of an eruption in the Portland/Vancouver metro area is very low.
Learn more: USGS Cascades Volcano Observatory