In 1956, the year Congress authorized the Interstate Highway System, there were 37,965 fatalities on U.S. roads—6.05 fatalities for every 100 million vehicle miles traveled (VMT). The construction of limited-access highways spurred travel by automobile, leading to an increase in the number of fatal accidents. Congress responded with a series of laws that have helped reduce the fatality rate by 80% over the past six decades. By 2014, the United States recorded only 1.08 fatalities for every 100 million VMT, although the rate ticked up to 1.13 per 100 million VMT in 2015 ( Table 1 ), and again in the first 9 months of 2016, when fatalities rose to 1.15 per 100 million VMT. Development of new motor vehicle technologies, investments in building safer highways and educating motorists, and improving emergency medical services all have contributed to reduced fatality rates. Congress has played a significant role in improving highway safety by directing the federal government to impose and enforce safety standards for motor vehicles. This effort has been at times controversial, and several large recalls have raised questions about the effectiveness of federal motor vehicle regulation. In the early decades of the automobile, U.S. vehicles were lightly regulated by a combination of state and private-sector standards. National regulation was generally not seen as appropriate; in the early 1900s, according to two historians of auto safety, it was widely believed that "the only useful and politically acceptable action Congress might take was to help the states and localities construct more and better roads." The Society of Automotive Engineers (SAE), a professional association founded in 1905, became the primary source of vehicle safety rules for many decades. State governments often used SAE recommendations to set their own standards for vehicle brakes, headlamps, and windshield wipers. At the same time, the rising number of highway deaths prompted a new interest in vehicle safety: between 1962 and 1964, Congress passed three safety bills into law, including a seat belt regulation. The new laws were only a precursor to broader federal regulation. Two publications also spurred interest in a greater federal role. Ralph Nader's 1965 book, Unsafe a t Any Speed: The Designed-in Dangers of the American Automobile , argued that cars were unnecessarily unsafe and that the auto industry should be regulated by a federal agency. Also influential was Accidental Death and Disability: The Neglected Disease of Modern Society , a National Academy of Sciences report that documented the impact of accidental injuries, including those by motor vehicles. Comprehensive vehicle safety legislation was passed in the form of the National Traffic and Motor Vehicle Safety Act of 1966. As approved unanimously by both houses of Congress and signed by President Lyndon B. Johnson, the legislation had two parts: 1. The Highway Safety Act of 1966 mandated that each state put in place a highway safety program in accordance with federal standards to improve driver performance, accident records systems, and traffic control. 2. The National Traffic and Motor Vehicle Safety Act of 1966 directed the Secretary of Commerce (later changed to the Secretary of Transportation when that agency was established in 1967) to issue safety standards for all motor vehicles beginning in January 1967. A National Traffic Safety Agency was established to carry out the provisions of the new law; it was renamed the National Highway Traffic Safety Administration (NHTSA) in 1970. Since its establishment, NHTSA has issued dozens of safety standards, including regulations affecting windshield wipers, hood latches, tires, brakes, seat belts, and airbags. Proposing and finalizing a NHTSA safety regulation can take many years: all NHTSA regulations follow the Administrative Procedure Act of 1946 (APA), which ensures that proposed rulemaking is publicized in the Federal Register , comments are taken and considered, and agency decisions are clearly explained. Court review of standards is allowed, and revisions to federal regulations must also follow the APA. NHTSA does not verify in advance that motor vehicles and parts comply with its standards. Instead, the law provides that "[a] manufacturer or distributor of a motor vehicle or motor vehicle equipment shall certify to the distributor or dealer at delivery that the vehicle or equipment complies with applicable motor vehicle safety standards prescribed under this chapter.... Certification of a vehicle must be shown by a label or tag permanently fixed to the vehicle...." Manufacturers are responsible for testing their vehicles and are liable for recalls and penalties if they are later found not to meet NHTSA's Federal Motor Vehicle Safety Standards (FMVSS). After a new model goes on sale, NHTSA buys a sampling from dealers and tests the vehicles at its own facilities to determine whether they comply. If NHTSA determines there is noncompliance, it can encourage the manufacturer to recall the model to correct the problem, or it can order a recall. In addition to promulgating motor vehicle standards and addressing vehicle defects, NHTSA's mission also includes providing assistance to states on traffic safety issues, such as drunk driving and distracted driving, and maintaining a comprehensive database about motor vehicle crashes. A recent NHTSA study estimated that passenger vehicle safety technologies associated with Federal Motor Vehicle Safety Standards (FMVSS) have saved 613,501 lives between 1960 and 2012. The study evaluated the effects of 31 motor vehicle technologies mandated by NHTSA, including dual master cylinders and front disc brakes, electronic stability control, energy-absorbing steering assemblies, seat belts, door locks, airbags, and side door beams. It estimated that the risk of a fatality in 2012 was 56% lower than in 1960, based on evaluation of the effectiveness of specific technologies in reducing occupant fatalities. The NHTSA report found seat belts, introduced in the late 1960s, to have been responsible for more than half of all the lives saved, 329,715, and that their effectiveness rose sharply after NHTSA required installation of combined lap and shoulder belts in place of simple lap belts in 1974. However, the study also highlighted the importance of other measures in addition to federal vehicle safety regulation: it estimated that the number of lives saved annually by seat belts rose from 800 to 6,000 after many states allowed police to issue tickets if a driver or passengers were not wearing seat belts. Every state but New Hampshire has enacted laws requiring seat belt use. The study notes that the full benefits of new federal safety standards may take many years to be felt. The passenger vehicle fleet turns over slowly; nearly half the cars and light trucks on the road are more than 12 years old. And standards can take many years to develop and issue. Although electronic stability control was introduced as standard equipment on one make of vehicle in 1998 and was subsequently adopted on some other makes, only 22% of light vehicles on the road were equipped with the technology in calendar year 2012. FMVSS required electronic stability control to be included in all new vehicles starting in model year 2012. The study estimates that more than 1,362 lives may be saved annually when all vehicles on the road utilize the technology, but this will not occur for a couple of decades. In a separate study in 2012, NHTSA evaluated the crashworthiness and crash avoidance performance of passenger cars and light vehicles, isolating the vehicle element in traffic safety improvements from human and environmental effects. The study did not focus solely on FMVSS-regulated technologies, but also included overall vehicle design and improvements initiated by manufacturers. Unlike NHTSA's Lives Saved by Vehicle Safety Technologies and Associated Federal Motor Vehicle Safety Standards, 1960 to 2012 , this study did not address specific technology and product sources of the improvements. The NHTSA report found that the likelihood of crashing in 100,000 miles of driving had decreased from 30% in a new model year 2000 vehicle to 25% in a new model year 2008 vehicle. The likelihood of escaping a crash uninjured improved from 79% to 82% in the same time period. The report contended that "the nationwide impact of these advancements is substantial" and that vehicle improvements between 2000 and 2008 prevented 700,000 vehicle crashes, prevented (or mitigated) injuries of 1 million occupants, and saved 2,000 lives in calendar year 2008 alone. In addition to promulgating and enforcing vehicle safety standards, NHTSA investigates vehicle defects that affect safety . NHTSA's Office of Defects Investigation (ODI) r eviews and investigates comp laints of alleged defects from vehicle owners , a utomakers , and other sources . There are several routes a potential recall complaint can take: Denial. When NHTSA 's analysis of petitions calling for defect investigations leads the agency to decide not to proceed , it publicizes the reasons for the denial in the Federal Register . Further R eview . If NHTSA determines there is reason to open an investigation of alleged safety -related defects , it looks further into the facts and ends with either a recommendation that the manufacturer recall the vehicle or a determination that there is no safety-related defect. If a safety defect is confirmed by NHTSA, most manufacturer s will initiate a recall ; if they fail to do so, NHTSA can initiate a recall itself. In addition to the NHTSA investigative process, manufacturers also conduct their own in ternal in vestigation s; if a manufacturer find s that a vehicle or component does not comply with a federal safety standard, it may issue its own recall to c orrect a safety defect before accidents are reported . The law establishing the motor vehicle safety program requires that a manufacturer of a defective vehicle or component notify the vehicle owner and fix the defect without charge. In practice, most recalls are issued by manufacturers, sometimes influenced by a NHTSA defect finding and sometimes solely by a manufacturer upon its own finding of a defect. Of the 1,039 recalls issued in 2016, 92 were issued by manufacturers influenced by a NHTSA finding , and 947 were issued based on a manufacturer's finding alone .