Grand Teton National Park in northwestern Wyoming includes the major peaks of the 40-mile-long (64 km) Teton Range as well as most of the northern sections of the valley known as Jackson Hole. It is only 10 miles (16 km) south of Yellowstone National Park. Along with surrounding National Forests, these three protected areas constitute the almost 18,000,000-acre (7,300,000 ha) Greater Yellowstone Ecosystem, one of the largest intact mid-latitude temperate ecosystems in the world. (From Wikipedia).