Source: "U.S. Revisits Its World Heritage Roots," Melinda Burns, Miller-McCune, March 28, 2009.
"for the first time since 1995, the U.S. Department of the Interior nominated two new sites for inclusion on the United Nation's World Heritage List of places of "outstanding universal value," a kind of Nobel Prize in the world of preservation. The two sites are George Washington's Mount Vernon estate on the Potomac River, and the Papahanaumokuakea Marine National Monument in the Northwestern Hawaiian Islands.......
"Since 2005, following a lapse of six years, the U.S. has been a member of the 21-nation World Heritage Committee, selecting and monitoring sites and making management recommendations. In 2007, the National Park Service became an associate member of the World Heritage Alliance, a partnership with the travel services company Expedia, Inc. to promote the sites."
In the early 1970s, under then-President Richard Nixon, the U.S. was the chief architect of and the first country to sign the World Heritage Convention, an international treaty administered by UNESCO that encourages all countries to protect places of exceptional ecological, scientific or cultural importance.