A hover conversion was an application to a ground vehicle to enable it to fly. Hoverboards were developed first, then the popularity of hoverboards led to the use of the technology for flying cars. The technology was originally developed between 1985 and 2015. The popularity of hover conversion led to problems like great trash storms, where many people would drop their trash from their hover cars while in flight. The excess of trash led to one hundred million Mr. Fusion units being sold, which were powered by the trash.