It would be logical to think that because the value of your home had declined, that the amount you pay in property taxes would decline also.... but think again.This is something most people don't understand. That just because the value of your property has declined, it does not mean that your tax bill will decline. Essentially an amount is set that is needed for budgets and taxes are collected to meet that amount (with a limit of a 1% tax increase). The value of your property just helps determine the portion of that tax being collected that a property owner will pay.
In addition to that residential properties also help make up deficiencies in commercial properties. Check out this great article.