and shrubs of over 2,000 species on and was founded in 1928. of Washington Park's trails are located in the arboretum. The Oregon Zoo, which opened at its current site in 1959, contains more than 2,500 animals of more than 200 species (including 15 endangered and 7 threatened species) in natural or semi-natural habitats. The zoo has a notable Asian elephant breeding program that grew out of the birth in 1962 of Packy, who in adulthood was the largest example of the species in North America. The Washington Park & Zoo Railway is a 1950s-era, narrow gauge railroad designed to carry passengers on a line between the Rose Garden and the zoo. It was opened in phases from 1958 to 1960. Currently, it is partially closed because of needed maintenance on retaining walls and culverts as it runs through the woods; until that work is done, it operates only within the zoo. The Portland Japanese Garden is a private traditional Japanese garden that opened in 1967. It was the most highly ranked Japanese garden in North America of more than 300 such gardens rated by experts from The Journal of Japanese Gardening in 2013. The World Forestry Center Discovery Museum offers educational exhibits on forests and forest-related subjects. It was founded in 1906 in the Forestry Building of the Lewis and Clark Centennial Exposition in Northwest Portland, and later established in Washington Park in 1971. Permanent exhibits explore the traits of forests around the world. Temporary exhibits have featured art (usually related to nature), ecology, wildlife and woodcrafts. The Oregon Vietnam Veterans Memorial was dedicated in 1987 to honor Oregonians who were killed or missing in action. The Rose Garden Children's Park is a playground that was completed in 1995 with $2 million in donations. It includes a large, colorful play structure designed to accommodate all children, including those with disabilities. Adjacent to the Children's Park is the Elephant House picnic shelter, converted from the old zoo's elephant barn. The Washington Park station is located beneath Les AuCoin Plaza, a scenic xeriscaped brick and stone terraced plaza located between the zoo and the World Forestry Center. The Washington Park Station is the only underground stop on the MAX Light Rail system and at below ground is the deepest transit station in North America. The station is accessed by four high-speed elevators. It opened for service on September 12, 1998. The