The Leopolds used to arrive at their shack outside Baraboo with nothing more than one suitcase containing clothes and toothbrushes.

The rebuilt chicken coop along the Wisconsin River inspired famed conservationist and author Aldo Leopold to put pen to paper and thought to action.

It is now recognized as one of the most historically significant sites in the nation.

As one of the final acts of the outgoing Bush administration, the shack and surrounding farm were placed on the National Historic Landmark list, joining 2,500 others nationwide and 39 others in Wisconsin.

"The shack was sort of an example of how you didn't need a palace and all these things surrounding you," said Leopold's daughter, 91-year-old Nina Leopold Bradley. "The general effect was (showing) that you can be very, very happy with very little stuff around you."

Leopold Bradley remembers summer nights in the 1930s and 1940s sitting around a campfire with her father, mother and four siblings, singing songs and strumming a guitar. Days during those weekend getaways were spent planting trees and restoring prairie.

"He didn't tell us this, but he was trying to restore this acreage to what it looked like before white men," Leopold Bradley said.

Her father's collection of essays, "A Sand County Almanac," was published just after his death in 1948 at age 61. The book - which has sold more than 2 million copies in 10 languages - describes Leopold's vision of a "land ethic," in which humans treat nature as they would another human being.

Leopold's children established the nonprofit Aldo Leopold Foundation in 1982 to advance that cause.

The foundation's executive director, Buddy Huffaker, said he hopes the National Historic Landmark declaration will bring awareness to Leopold's call for "human responsibility toward the land."

"The shack demonstrates the realization of Leopold's land ethic philosophy and his concept of land health," Huffaker said. "We hope the designation will help more people to learn about and appreciate the continued importance Leopold's legacy has for us today and into the future."

The shack and farm have been preserved by the foundation and is still surrounded by much of the same historic landscaping and vegetation present during Leopold's time.

Sauk County Historical Society President Paul Wolter said the recent declaration sets the Leopold shack apart from the 80,000-plus properties listed on the National Register of Historic Places.

"A site can be on the national register and only be significant to your community and your state," Wolter said. "But to become a National Historic Landmark, you have to prove national significance."

The shack was among nine sites in nine states placed on the list last Friday by outgoing U.S. Department of the Interior Secretary Dirk Kempthorne.

Only two other Sauk County properties are on that list: the Ringling Brothers Circus Winter Quarters in Baraboo and the Van Hise Rock in Rock Springs.

Columbia County has one: The Farmers' and Merchants' Union Bank in Columbus. Fountain Lake Farm in Marquette County also is on the list.