According to Official Guinness Records,
The longest nail bar is 47.42 m (155 ft 6 in) and was achieved by OPI Products, Inc. (USA) in Santa Monica, California, USA, on 21 October 2017. Fifty nail technicians provided 501 manicures during the eight hours the nail bar was open, with guests including Disney Channel actress Peyton List.
For a complete list of 2017 records, please visit 2017 Guinness Records in United States.