Nong Khai province was formerly the northernmost of the northeastern (Isan) provinces (changwat) of Thailand until its eight eastern districts were split off to form Thailand's newest province, Bueng Kan province, in 2011. Nong Khai province lies in upper northeastern Thailand. Nearby provinces are : Bueng Kan, Sakon Nakhon, Udon Thani, and Loei. To the north it borders Vientiane province, Vientiane Prefecture, and Bolikhamsai province of Laos.