The most people to do jumping jacks in 24 hours is 300,265 at 1,050 locations worldwide as part of the "Let's Jump!" event organised by National Geographic Kids (USA) from 11-12 October 2011. The record attempt was launched by First Lady Michelle Obama leading 464 children doing jumping jacks for 1 minute at the White House in Washington, D.C., USA, on 11 October 2011.
The event was part of the First Lady's "Let's Move!" initiative to fight childhood obesity. Today Show personality Al Roker and Olympic figure skater Michelle Kwan served as independent witnesses at the White House attempt. Each location provided statements from independent witnesses, supervisors and timekeepers as well as photos. Example evidence packet, spreadsheet of locations and totals, and media coverage report attached.
Comments below may relate to previous holders of this record.