Depending on where you live, it might be illegal for you or your child to ride a bicycle without wearing a helmet. There are no federal laws mandating bicycle helmet use in the United States, although many states and localities have mandatory bicycle helmet laws applicable to minors. Some cities and municipalities also have laws mandating that people of all ages wear helmets when riding a bicycle. However, 13 states have no statewide or local laws mandating bike helmet use for children or adults.Since 1987, many states and localities have passed their own bicycle helmet laws, mostly limited to children under 18. According to the Bicycle Helmet Safety Institute, 21 states have statewide laws that require minors to wear a helmet when riding a bicycle, but no state has a statewide law requiring adults to where bicycle helmets. Laws vary by state; some states require that all minors under 18 wear helmets when bicycling and other states require only children under 12 to wear helmets. The following states have statewide bike helmet laws for minors: Alabama, California, Connecticut, Delaware, Florida, Georgia, Hawaii, Louisiana, Maine, Maryland, Massachusetts, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oregon, Pennsylvania, Rhode Island, Tennessee and West Virginia.While there are no statewide laws requiring adults to wear bike helmets, some cities have laws mandating helmet use for bicyclists of all ages. Sixteen states have no statewide laws mandating bicycle helmet use but have laws in some localities -- including certain cities, municipalities and parks -- requiring either minors or both minors and adults to wear helmets. For example, while Texas has no statewide law, Arlington, Austin, Houston and several otherTexas cities have laws requiring minors to wear helmets and Dallas has a law requiring people of all ages to wear a helmet when riding.Since bicycle helmet laws vary by both state and locality, it is important to check the local laws in your region to determine whether it is illegal for you or your child to ride a bike without a helmet -- that is, unless you live in states where there are no state or local laws mandating bike helmet use. According to the BHSI, as of June 2010, 13 states have no state or local bicycle helmet laws applicable to children or adults. They are Arkansas, Colorado, Idaho, Indiana, Iowa, Minnesota, Nebraska, North Dakota, South Dakota, South Carolina, Utah, Vermont and Wyoming.There is some debate in the United States and other countries over whether bicycle helmet laws should exist. According to the National Highway Traffic and Safety Administration, wearing a helmet is the single most effective way to prevent head injury resulting from a bicycle crash. Accordingly, some safety advocacy groups, including the BHSI, take the position that bicycle helmets should be mandatory for people of all ages. However, some researchers, including Piet De Jong, a mathematician at Macquarie University in Sydney, Australia, argue that bicycle helmet laws might do more harm than good. According to a 2010 paper authored by De Jong and published in "Social Science Research Network," mandatory helmet laws often deter would-be bicyclists from bicycling and, depending on the safety of the riding environment, the net societal decrease in cardiovascular benefits resulting from helmet laws might outweigh the health benefit of reduced head injuries.