According to Official Guinness Records,
The largest heart formation consisted of 11,166 participants and was achieved by the state of Nuevo León at an event organized by Multimedios (Mexico) at Parque Fundidora in Monterrey, Nuevo León, Mexico, on 27 February 2010.
30,000 red headscarves were handed out by Multimedios TV and radio in the days leading up to the event and were worn by participants, who were also dressed in red, for aerial photographs. The event featured numerous musical performances and was broadcast live on Multimedios.
For a complete list of 2010 records, please visit 2010 Guinness Records in Mexico.