What is the 'Dark Store Theory' and how is it costing Pennsylvanians more in local taxes?

(WTAJ) -- If there's one thing Pennsylvanians can agree on, it's taxes, and a state senator wants big-box stores to pay their fair share by banning what's called the "Dark Store Theory." The theory is actually a local tax practice that allows large retailers to have their properties assessed as vacant, or "dark," during the [...]