Cities are rushing to replace their legacy street lights with "smart" LED fixtures that could one day be able to find you a parking space, monitor air quality, and announce an oncoming thunderstorm.

Why it matters: Despite a bumpy and controversial start to some smart street light programs, cities are saving tons of money on energy by banishing traditional bulbs — and may soon be able to turn a profit by monetizing data from smart LED sensors or leasing space on light poles.

The big picture: There's been lots of hype about "smart cities," where connected technology helps governments serve us better — but also lots of money wasted on expensive projects that fizzled or caused public outcry over police use of camera surveillance.

+INFO: Axios