This paper models the effects on crash fatalities and costs of 20 years of legislative actions resulting from Federal and state advocacy efforts. We catalogued road safety laws passed between 1990 and 2009 and motorcycle helmet law repeals that advocacy efforts narrowly defeated. We used NHTSA's estimates of lives saved by airbags and published estimates of the percentage reduction in related crash fatalities associated with each type of law. State by state and year by year, from the actual fatality count for the year, we modeled how many fatalities each state's laws averted. We assumed, somewhat shakily, that the percentage reduction in nonfatal injury costs would mirror the fatality reduction. We used crash cost estimates for 10 years between 1990 and 2008 to estimate total crash costs from 1990-2009. The costs were built from NHTSA's estimates of cost per crash. The state laws passed included 113 occupant protection laws, 131 impaired driving laws, and 76 teen driving laws, plus a Federal airbag mandate. These laws saved an estimated 120,000 lives. The life-saving benefits accelerated as the number of laws in force grew. By 2009, they resulted in 25% fewer crash fatalities. The largest life-saving benefits sprang from airbag, belt use, and impaired driving laws. Laws that affect narrow subpopulations had more modest impacts. The laws reduced insurance costs by more than $210 billion and saved government an estimated $42 billion. Including the value of lost quality of life, estimated savings exceeded $1.3 trillion. Legislative advocacy is truly a spark plug in the safety engine.