Kids Count, a project of the Casey Foundation aimed at measuring child well-being in America, has ranked New Hampshire #1 in six of the seven past surveys since 1999. The 2004/2005 year was the only year New Hampshire dropped from the first spot, taking second. It reclaimed it’s #1 spot the following (most recent) year.
Additional Sources:
http://www.kidscount.org/datacenter/profile_results.jsp?r=31&d=1