Fireworks during Thunder Over Louisville, April 18, 1998. Started in 1989 as the kickoff show for the Kentucky Derby Festival, Thunder is the largest annual pyrotechnics display in North America. The show is larger than the opening and closing ceremonies of the Atlanta and Barcelona Olympics combined. Along with an afternoon air show, it attracts an estimated average attendance of half a million people to downtown Louisville. This 1998 show, featured 46 tons of fireworks. Today, eight tractor trailers are filled with nearly 60 tons of fireworks shells. The 2018 show will be Saturday. Photo by Mark Cornelison | staff