Boeing executives and more than 500 employees, suppliers, union representatives and government officials joined China Southern Airlines to celebrate the 4,000th Next-Generation 737 at a special event last week at Seattle’s Boeing Field.

The 4,000th Next-Generation 737 jetliner off the 737 production line in Renton was to be delivered this week to China Southern Airlines, headquartered in Guangzhou, China.

“The Next-Generation 737’s success is the result of years of expertise that thousands of employees continue to build into every Boeing 737 used in private, government and commercial service,” said Beverly Wyse, vice president and general manager of the 737 program, in a Boeing press release.

“It is an incredible milestone to be delivering our 4,000th Next-Generation 737. We thank China Southern Airlines and all our customers who have made the 737 the world’s most popular jetliner.”

China Southern Airlines is commemorating a milestone as the plane will be the 75th 737 delivered directly to the airline. The carrier has an additional 45 737-700/-800s on order. China Southern is the largest airline in China and operates a fleet of 450 airplanes, making it the sixth largest carrier worldwide, according to the press release.

“China Southern and Boeing have built an excellent relationship and we are honored to be the recipient of Boeing’s 4,000th Next-Generation 737 airplane,” said Dong Suguang, executive vice president, China Southern Airlines. “The Next-Generation 737s provide a solid foundation to China Southern’s modern, fuel-efficient and economical portfolio of commercial jetliners.”

The 4,000th Next-Generation 737 is a 737-700 model that seats 126 passengers in a two-class configuration with the new Boeing Sky Interior.

More 737s have been produced than any other commercial jetliner in history and continues to hit the record books as the program produces airplanes at record rates, according to the company.

The gap between each Next-Generation 737 record delivery is shrinking. It took Boeing three years and one month between the 2,000 and 3,000, while the gap between the 3,000th and 4,000th delivery is just two years and eight months. With 737 production rates increasing incrementally to a record 42 airplanes a month in the first half of 2014, the gap will continue to close, according to the company.

The Next-Generation 737 family has won more than 6,600 orders and has a diverse backlog exceeding 2,600 airplanes.

With more than 5,550 airplanes in service, the 737 family represents more than a quarter of the total worldwide fleet of large commercial jets flying today. More than 358 airlines in 114 countries fly 737s.