Most of the foreigners living outside of Japan know that the biggest city in Kyushu is Fukuoka city, the capital of Fukuoka prefecture. Population is more than 1.5 million, sixth populated city in Japan and Fukuoka metropolitan area is the fifth populated area.
The first city in Kyushu to excess 1 million inhabitants was Kitakyushu city which Kokura, Moji, Tobata, Yawata and Wakamatsu cities merged in 1963. KItakyushu became the first city more than 1 million inhabitants out of 3 major greater metropolitan areas(Tokyo, Nagoya and Osaka) and not capital of the prefecture.
However, Kitakyushu's population became 2nd in Fukuoka prefecture in 1978 and the peak of the Kitakyushu's population was in 1979, reaching 1.08 million. National census in 2015 was just 0.96 million inhabitants. KItakyushu is the only city over 1 million inhabitants which population is decreasing annually. It is expected to be 0.78 million inhabitants in 2040.
On the other hand, Fukuoka city became more than 1 million inhabitants in 1975 and passed the rival city in 1978 and then steadily increased its population. This is due to Kitakyushu is much industrial city but Fukuoka is educational and commercial city.
By the way, the main station of Fukuoka city is not Fukuoka station. Actually there is no Fukuoka station in Fukuoka either. There was a town called Hakata since the beginning of the middle age. Then, feudal lord Kuroda clan built a castle and named it as Fukoka castle. Since then the people called east side of Nagagawa(Naka river) as Hakata and west side as Fukuoka. Hakata was the commercial town for merchants and Fukuoka was the town for samurai. Then, both towns merged and became Fukuoka city in 1889.
When the first railway in Kyushu opened in 1889, the station in Fukuoka city was named Hakata station instead of Fukuoka station due locating at Hakata district. The municipal assembly later on tried to rename the city to Hakata city but finally it was rejected by the votes by the members of the assembly. On the other hand, no one tried to rename Hakata station to Fukuoka station due to its popularity. Many Japanese even in Kyushu use Hakata than Fukuoka as like "Are you coming to Hakata?" instead of "Are you coming to Fukuoka?". Most of the hotels in Fukuoka city use Hakata as part of the hotels' names too. However, the atlas is shown as Fukuoka.
People think there was Hakata city in the past but the truth is that the city's name was already Fukuoka since the opening of the Hakata station. There are main stations which are not named after city names or the previous city name. For example, Kichijoji station in Musashino city.
However, Hakata station is the only station located in prefectural capital which is not using current nor previous city name in Japan.
By the way, the airport in Fukuoka is Fukuoka airport, not Hakata airport. However, port is called Hakata port and there are daily speed boat connections with Pusan, South Korea.