According to Official Guinness Records,
The longest line of swing sets is 51 and was achieved by Backyard Discovery and Big Brothers Big Sisters of Broward County (both USA), in Fort Lauderdale, Florida, USA, on 29 April 2016. The line of swing sets was 171.52 metres. This record was attempted to raise awareness about children's health and promote the benefits of children playing outdoors.
For a complete list of 2016 records, please visit 2016 Guinness Records in United States.