On the Honshu side of the water is Shimonoseki, which contributed "Kan" to the name of the strait) and on the Kyūshū side is Kitakyūshū, whose former city and present ward, Moji, gave the strait its "mon". The straits silt up at the rate of about 15 centimetres per annum, and dredging has made it possible to build the New Kitakyushu Airport at low cost.
The total population of the Kanmon area is about 1.3 million, counting the whole of Kitakyushu (approx one million) and Shimonoseki (approx 300,000), although detailed definitions vary widely, see Fukuoka-Kitakyushu. A new airport opened in Kitakyushu on March 16, 2006 which is expected to bring further prosperity in the form of increased tourism and trade to the area.
The Kanmon Straits Summer Fireworks Viewing dwarfed all the neighbouring ones with no less than 13,000 fireworks being let off in 2005, when the 18th annual display was held on August 13. There were large crowds of more than one million-watching from both sides of the straits. The Fireworks Festival is held on August 13 every year. The 20th festival in 2007 was televised by NHK and broadcast live nationwide in hi-vision.