Jackson Hole, fertile Rocky Mt. valley, c.50 mi (80 km) long and 6 to 8 mi (9.6–12.8 km) wide, NW Wyo., partly in Grand Teton National Park. Jackson Lake, 39 sq mi (101 sq km), a natural lake through which the Snake River flows, was dammed in 1916 to control the river's flow. Now a summer and winter resort area that attracts many tourists every year, the valley has been popular with hunters and trappers from the time American trapper David Jackson, for whom it was named, wintered there in 1828–29. In the late 1880s, Jackson Hole was settled; two homesteads have been restored as historic sites. The National Wildlife Art Museum is just N of the town of Jackson. The National Elk Refuge, est. 1948, is the winter home of the largest elk herd in North America. Many animals and birds inhabit the area, including the bald eagle and the rare trumpeter swan.