A U.S. city of one million needs about $100 per year per person to replace public transit fares. This amount of tax would be recovered many times over by very small percentage reductions in other costs. Many studies show that increased use of public transit improves health. Health care costs would need to go down less than one percent. Free transit would lower collision and congestion costs as well. We put the numbers in a spread sheet. Take a look. The good news is the payback starts immediately.