Milwaukie History Railroads Ecosystem Industrial Development Works Program Administration Flooding Plan Restoration Spring Water Corridor Teens on the Trail Memories Childhood Memories Development Recreation & Restoration Courtesy of Portland Park Bureau The Springwater Corridor is a major segment of the 40-mile loop. In 1903, the Olmstead Brothers made provisions for a nature trail that would encircle the city of Portland. In recent years, local agencies have collaborated to complete segments of the trail, which has now grown to about one hundred and sixty miles, though it still retains the "40 mile loop" moniker. The trail accommodates a wide range of uses including walking, jogging, bicycling and even horse riding. Along the route one is likely to see various wildlife and vegetation, as well as remnants of the work done by the Works Projects Administration in the 1930s.