This big yet easy adventure is a lot of fun if you have a spare day in Portland.
While Dawn visited friends in Hillsboro, Hayden and I opted to stay in Portland to Christmas shop and explore. In doing online research of things to do in the city, I learned of the 4-T trail. The 4 Ts of the trail are Tram, Trolley, Train, and Trail. We were staying downtown near Pioneer Courthouse Square, so our first T would be the MAX train. The train took us inside the Robertson Tunnel where you get off at the Washington Park/Oregon Zoo MAX station. From here you take the elevator 260 feet up to the Oregon Zoo.
Before I get into any specifics about directions or anything like that, I'll just say enjoy my post, but get directions and information from the 4-T trail website. This is the site I used when we went to navigate the trail. We only got slightly sidetracked as we were looking for the Tram near OHSU.
One final note: As of this writing, the Tram is closed on Sundays in the winter. Check the tram's website for schedule. You wouldn't want your fourth T to be a Taxi!