Much like motorcycle helmet laws, bicycle helmet laws vary state-to-state. Twenty-one (21) states and the District of Columbia require bicycle helmets for children (mostly 15 and younger, with some exception).
States that have bicycle helmet laws in all counties include the following:
• District of Columbia
• New Hampshire
• New Jersey
• Nw Mexico
• New York
• North Carolina
• Rhode Island
• West Virginia
In Florida, §316.2065(3)(d), Florida Statutes, requires all bicyclists under the age of 16 to wear a helmet. The law says:
A bicycle rider or passenger who is under 16 years of age must wear a bicycle helmet that is properly fitted and is fastened securely upon the passenger’s head by a strap, and that meets the standards of the American National Standards Institute (ANSI Z 90.4 bicycle helmet Standards), the standards of the Snell Memorial Foundation (1984 Standard for Protective Headgear for Use in Bicycling), or any other nationally recognized standards for bicycle helmets adopted by the department.
As used in this subsection, the term “passenger” includes a child who is riding in a trailer or semitrailer attached to a bicycle. In addition, law enforcement officers in Florida may issue citations and fines for cyclists who fail to comply with the above bicycle law, although the ticket and fine can be dismissed if the rider later shows proof of the purchase of a helmet.
States that have bicycle helmet laws specific to some counties include the following states which are highlighted in orange.
The NHTSA put together a PDF highlighting “Bicycle Helmet Use Laws: Lessons Learned from Selected States” which includes a case study from my home town of Jacksonville, Florida (Duval County).