Bill Weber, age 10, of Albuquerque, N.M., for his question:

WHEN WAS YELLOWSTONE NATIONAL PARK ESTABLISHED?

The Yellowstone region was obtained by the United States government as part of the Louisiana Purchase in 1803. John Colter, a member of the Lewis and Clark expedition, was probably the first white person to see Yellowstone.

In 1870, General Henry Wasburn, the surveyor general of the Montana Territory, led an expedition to check out reports from trappers about spouting geysers, hot springs and bubbling mud pots. In 1871, a government expedition led by Ferdinand Hayden, a geologist, documented the unusual features of the area.

In 1872, Congress passed a bill to establish the park and preserve its natural resources. Civilian superintendents administered the park for the first few years, but they were unable to stop widespread hunting and trapping there.

The Army took over control of the park in 1886 and started to protect the wildlife. A detachment of cavalry occupied the park until 1916, when Congress established the National Park Service.

A superintendent, appointed by the director of the National Park Service, today manages Yellowstone. He is assisted by park rangers, naturalists and a maintenance staff.