The 13-cent New Hampshire State Flag (Scott 1641) depicts the state flag adopted in 1909. The stamp features the state seal on a blue field surrounded by laurel leaves. The nine stars commemorate New Hampshire as the ninth colony to join the United States. The flag changed in 1931 when the state's seal was modified.
Scott 2005 Specialized Catalogue of U.S. Stamps and Covers
SHG Resources (http://www.shgresources.com/nh/symbols/flag/)