ICF International's study analyzes the amount of petroleum saved by the use of public transportation systems in the United States. The analysis reveals that public transportation currently saves 1.4 billion gallons of gasoline annually. The study further examines actual savings in household budgets attributable to public transportation use and included factors that influence travel such as income, household size, neighborhood density, and the number of workers in the household. It concludes that public transportation use correlates with 16 fewer miles driven per day, per household. This amounts to an estimated $1,400 per year in annual fuel costs. Two-worker households in which one worker uses public transportation have the opportunity to save substantially more if they have only one car. These families can save an estimated $6,200 per year, accounting for both public transportation use and vehicle ownership.