From the Disney Parks official YouTube Page:
A look back through the Walt Disney World video archives to- 1999 and a night you could’ve been driving toward Magic Kingdom Park with Pete’s Dragon in the lane next to you. In May of 1999, a few weeks before Main Street Electrical Parade started making nightly appearances in Florida, hundreds of cars lined an interstate for an overnight road test. Many of the Main Street Electrical Parade vehicles and cars driven by Walt Disney World cast members joined a ceremonial caravan toward the park. It was quite a sight. See for yourself!
Main Street Electrical Parade debuted in Anaheim at Disneyland back in 1972 and after a 24-year run, closed in 1996. In May 1999, after technical and electrical upgrades, Main Street Electrical Parade made the move to Magic Kingdom, just in time for the start of the Millennium Celebration. Disney’s Main Street Electrical Parade begins a limited engagement for Summer Nightastic! at Walt Disney World beginning June 6 and continuing through Aug. 14.