Udon Thani

Udon Thani(Thai:อุดรธานี,pronounced[ʔù.dɔ̄ːntʰāː.nīː]) is a city inIsan(Northeast Thailand), the capital ofUdon Thani Provinceand the sixth largest city inThailand. The city municipality (thesaban nakhon/city proper) had a population of 130,531 people as of 2019, while Udon Thani's urban area,Mueang Udon Thani, has a population of approximately 400,000. 
Udon Thani is one of four major cities in Isan, the others beingNakhon Ratchasima,Ubon Ratchathani, andKhon Kaen. Together they are known as the "big four of Isan".
Udon is approximately 560 km fromBangkok. It is a major official and commercial center in northernIsan, Thailand, and the gateway toLaos,northern Vietnam, andsouthern China.
The city's economy was boosted by the proximity toUdorn Royal Thai Air Force Baseduring theVietnam Warand retains reminders of that time in the form of bars, coffee shops, and hotels. "Udon sort of became likePattayawhen theGIsarrived," said a local architect."Restaurants serving Western cuisine, hotels and nightclubs sprouted up everywhere to meet their needs. It was an extremely busy city back then."
The BBC has reported thatUdon Thani's Royal Air Force Basewas the site of a CIAblack site, known to insiders as "Detention Site Green", used to interrogateAbu Zubaydah, Saudi-born Palestinian, believed to be one ofOsama bin Laden's top lieutenants. In December 2014 theUnited States Senate Select Committee on Intelligence(SSCI) published an executive summary of a secret 6,000-page report on CIA techniques. The report alleges that at least eight Thai senior officials knew of the secret site. The site was closed in December 2002.
Earlier reports alleged that aVoice of Americarelay station in a rural area of Udon Thani Province,Ban Dung District, was theCIAblack site.
Udon Thani town municipality (thesaban mueang) with an area of 5.6 km(2.2 sq mi) was established on 15 March 1936.On 27 May 1953, the area covered by the municipality was increased to 8.3 km(3.2 sq mi).As a result of the town's continuing growth, the total area of the municipality was enlarged for the second time to 47.7 km(18.4 sq mi). on 31 December 1993.On 25 September 1995 Udon Thani was upgraded to city municipality (thesaban nakhon),and  is divided into 21 sub-districts (tambons), which are further subdivided into 248 villages (mubans). (chumchon), 130,531 people in 60,659 households.
Udon Thani International Airport, close to the city centre (within the ring road), serves a number of domestic airports:Chiang Mai International Airport,U-Tapao International Airport(Pattaya), and Phuket, with approximately 24 daily flights to Bangkok (Don Mueang InternationalandSuvarnabhumi Airport).During  the 2020-2021COVID-19 pandemicflights were reduced to 10-14 daily toBangkok airports only.
Udon Thani railway stationin the city centre receives four trains daily fromBangkok railway station(Hua Lamphong) including overnight sleepers.
Asia Pacific Potash Corporation (APPC), a wholly owned subsidiary of Italian-Thai Development PLC, owns the concession to theUdon Northand Udon Southpotashmines and plans to develop them.Potash deposits in northeast Thailand are believed to contain the world's third-largest—after Canada and Russia—unexploited potash reserves.Potash is one of the main components of agriculturalfertilizer.
Udon Thani has atropical savanna climate(Köppen climate classificationAw). Winters are fairly dry and very warm. Temperatures rise until April, which is hot with the average daily maximum at 36.2 °C (97.2 °F). Themonsoonseason runs from late-April through early-October, with heavy rain and somewhat cooler temperatures during the day, although nights remain warm. The range of reliably recorded temperatures in the city is from 2.5 °C (36.5 °F) to 44.1 °C (111.4 °F).