At night , the bridge is illuminated by 200 sodium vapor lights along its " M " shape structure . The bridge was first illuminated on September 5 , 1986 , after $ 373,000 of private funds had been raised to fund the cost and installation of the lights . Due to some river traffic having issues with the lights at night reflecting on the water , the city installed a remote switch to toggle the lights on and off briefly while the vessel passes under the bridge . During the 2011 Mississippi River floods , the bridge became dark for about 2 months because the transformers that supply the electricity for the lights were removed to prevent damage to them by flood waters . The bridge was re-lit in a ceremony which occurred on June 21 , 2011
2011 Mississippi River floods
2011 Mississippi River floods
Hernando de Soto Bridge