The final six were:

(a) The percentage of the total state highway mileage that is rural
(b) The percent increase in motor vehicle registration
(c) The extent of motor vehicle inspection
(d) The percentage of state-administered highway that is surfaced
(e) The average yearly minimum temperature
(f) The income per capitaThese are placed in descending order of importance. These six accounted for 70% of the variations in the rate. The rate of traffic deaths in the United States doubled from 1915 to 1921 when it reached 12 deaths per 100,000 Americans. A century later, in 2021, the annual death rate was 12.9 per 100,000. Safety focus on protecting the occupants of automobiles has victimized bicyclists and pedestrians. From 2010 to 2019, fatalities rose 36% for bicyclists and nearly doubled for those on foot. Reasons include larger vehicles, faster driving, and digital distractions making walking and biking in the United States far more dangerous than in other comparable nations.Early 20th century "judges defended pedestrians rights in city streets. The convenience of drivers was no grounds for infringing these rights. Any motorist driving too fast to avoid injuring or killing a pedestrian was regarded as speeding.... (More recently) there has been a tacit agreement in the United States to treat the right to walk as dispensable, (tending) to attribute such deaths to individual failures for which individuals alone — reckless drivers or careless pedestrians — are responsible. "The worlds first autonomous car incident resulting in the death of a pedestrian occurred on 18 March 2018 in Arizona.
These issues may make those who have been in a crash afraid to drive again. In some cases, psychological trauma may affect individuals lives, causing difficulty going to work, attending school, or performing family responsibilities. Causes
Road incidents are caused by a large number of human factors such as failing to act according to weather conditions, road design, signage, speed limits, lighting conditions, pavement markings, and roadway obstacles. A 1985 study by K. Rumar, using British and American crash reports as data, suggested 57% of crashes were due solely to driver factors, 27% to combined roadway and driver factors, 6% to combined vehicle and driver factors, 3% solely to roadway factors, 3% to combined roadway, driver, and vehicle factors, 2% solely to vehicle factors, and 1% to combined roadway and vehicle factors. Reducing the severity of injury in crashes is more important than reducing incidence and ranking incidence by broad categories of causes is misleading regarding severe injury reduction. Vehicle and road modifications are generally more effective than behavioral change efforts with the exception of certain laws such as required use of seat belts, motorcycle helmets, and graduated licensing of teenagers. Human factors
Human factors in vehicle collisions include anything related to drivers and other road users that may contribute to a collision. Examples include driver behavior, visual and auditory acuity, decision-making ability, and reaction speed. A 1985 report based on British and American crash data found driver error, intoxication, and other human factors contribute wholly or partly to about 93% of crashes.