People inside the new Beijing Daxing International Airport during its first day of operation in Beijing on September 25, 2019.AFP | Getty ImagesThe Hartsfield-Jackson Atlanta International Airport is about to get some serious competition. It’s held the title of the world’s busiest airport in terms of passenger traffic since 1998 — but China’s newest airport is trying to challenge that.China opened Beijing Daxing Airport on Wednesday, the second international airport in the capital city. When it reaches full operational capacity, expected in the next several years, 100 million passengers are forecast to go through the airport annually.The International Air Transport Association expects Asia Pacific to be the biggest driver of air passenger demand in the 20 years through 2035.Specifically, China will replace the U.S. as the world’s largest aviation market in about five years, the association predicts. The market is defined by traffic to and from the country, as well as domestic flights within its borders.The bulk of the growth in Chinese air travel came in the three decades since the government began earnest efforts to reduce state control of the economy and open up its market to foreign access.In 1974, the earliest data available from The World Bank, just 710,000 passengers were carried in China. That climbed to 11.1 million in 1989, and multiplied manifold to 611.4 million in 2018, the bank’s data showed.The existing Beijing Capital International Airport opened in 1958. It already holds the title of second-largest airport by number of passengers, according to Airports Council International.The number of passengers in Beijing Capital grew 5.4% on year to 101 million in 2018 — that’s compared to a year-on-year growth of 3.3% growth to 107 million for Atlanta over the same period, the data showed.Daxing International Airport was built to expand the capital city’s capacity for visitors and alleviate pressure on the main airport. The first construction phase was completed in less than five years. Initial capacity for the star-shaped terminal building is 45 million passengers, but there are plans to expand the airport’s capacity to 72 million by 2025, and ultimately 100 million, according to the Centre for Aviation.Chinese airlines grow rapidlyChina’s airlines are also climbing quickly into the ranks of the world’s largest.China Southern and China Eastern saw their revenue passenger kilometers, a measure of airline traffic, jump by more than 80% in the last 5 years, according to data for June from the International Civil Aviation Organization. That puts the two Chinese airlines among the fastest growing since 2014.China Southern and Air China now rank among the 10 largest airline groups in the world, ICAO data showed.In the U.S., United, Delta and American hold the top three spots, while Germany’s Lufthansa is also a fast-growing group, ranking fourth as of June 2019.However, due to passenger volume, air traffic control and other factors, China’s airports have been notorious for delays. In August, the five global airport hubs with the longest average delay time – ranging from about 84 minutes to 97 minutes — were all in mainland China, according to data from FlightStats.— CNBC’s Yen Nee Lee contributed to this report.