Why is automobile insurance in Philadelphia so damn expensive?

The premiums for automobile insurance vary according to city. Large numbers of motorists without insurance can lead to high premiums in some cities, while high premiums may cause many motorists to avoid becoming insured in other markets. A noncooperative equilibrium model produces inefficient equilibria with uninsured motorists and high premiums that are actuarially fair. Markets that have low density and high income have a lower probability of poor equilibrium.