記念切手（NATURE OF AMERICA)

この記念切手のシリーズは1999年から毎年発行されてきました。
１）Sonoran Desert 04/06/1999 Tucson, Arizona

２）Pacific Coast Rain Forest 03/28/2000 Seattle, Washington

３）Great Plains Prairie 03/29/2001 Lincoln, Nebraska

４）Longleaf Pine Forest 04/26/2002 Tallahassee, Florida

５）Arctic Tundra 07/01/2003 Fairbanks, Alaska

６）Pacific Coral Reef 01/02/2004 Honolulu, Hawaii

７）Northeast Deciduous Forest 03/03/2005 New York, New York

８）Southern Florida Wetland 10/05/2006 Naples, Florida

９）Alpine Tundra 08/28/2007 Estes Park, Colorado

１０）Great Lakes Dunes 10/02/2008 Empire, Michigan

１１）Kelp Forest 10/01/2009 Monterey, California

１２）Hawaiian Rain Forest 09/01/2010 Hawaii National Park