Portland's Forest Park is the largest urban park in the United States, covering over 5,000 acres that include 70 miles of trails for hiking, walking and biking. Even in the middle of winter, the park was full of greenery, mostly from the moss-covered trees and ferns. After an hour's hike up the trail, we only saw a tiny fraction of the park. It was full of people of all ages, young and old, runners, people walking their dogs, families with small children. We were on MacLeay Trail which had a beautiful stream, native plants throughout and one brown squirrel.