McKenzie Pass - Belknap Crater Lava Flows, Oregon
There are many geologically recent lava flows in the Cascades. The most spectacular ones I've seen are the the flows around Belknap Crater in central Oregon. The Belknap Crater flows are also really easy to get to. A series of eruptions around the Belknap Crater from 1,000 to 2,000 years ago covered dozens of square miles with lava on and around the top of the Cascade range. The lava flowed around hills creating islands of trees in the lava wasteland that are visible today. Highway 242 from Sisters to Eugene crosses the Cascades at the McKenzie Pass. As the highway traverses the pass it travels first alongside and then across the lava field. The Dee Wright Observatory in the middle of the Lava Fields has spectacular panoramic views of the lava and nearby mountains. The Pacific Crest Trail crosses highway 242 just West of the observatory. The trail crosses both the lava and the forested islands and makes a really interesting afternoon hike. Highway 242 over the McKenzie pass is closed in winter.
Lava Butte near Bend (picture below) is another easy place to see recent lava flows in Oregon. There is a road that goes to the top of Lava Butte. The Lava Lands visitor center and trails around the flows are at the bottom of Lava Butte just off highway 97. It's generally pretty crowded and you have to get on a wait list to drive to the top of the Butte (you get a ticket for a scheduled time slot).