1975 Universal helmet laws in 47 states and the District of Columbia. All but three states had universal helmet laws (IL, IA, CA).
1976 Congress removed the financial penalties on federal funds that were contingent upon states’ enactment of helmet laws. $17.5 Billion in federal highway funds to the states was no longer linked to states’ compliance with helmet laws. This catalyzed a widespread repeal of helmet laws.
In 1977, New Hampshire reduced its helmet law to a partial law for riders under 18 years until the federal government no longer required a helmet law as a condition for federal funding.
Upon repeal of the federal penalty in 1995, NH became a state with no helmet law.
Source:
https://www.cns.org/sites/default/fi...nal_050717.pdf