Digital Commons Network^™

We estimate auto accident externalities (more specifically insurance externalities) using panel data on state-average insurance premiums and loss costs. Externalities appear to be substantial in traffic-dense states: in California, for example, we find that the increase in traffic density from a typical additional driver increases total state wide in-surance costs of other drivers by $1,725–$3,239 per year, depending on the model. High–traffic density states have large economically and statistically significant externalities in all specifications we check. In contrast, the accident externality per driver in low-traffic states appears quite small. On balance, accident externalities are so large that a correcting Pigouvian …

Why don’t people give more to charity? One reason is that the problems will be there whether individuals give or not. Here is a policy--inspired by the matching grants that charities use so effectively--that could actually make a real difference.