Ban Houayxay, also Huoeisay, Houei Sai or Huay Xai and, is the capital of the Lao province of Bokèo, on the border with Thailand. The town lies on the Mekong River opposite Chiang Khong in Thailand. The Fourth Thai–Lao Friendship Bridge at Ban Houayxay, which opened in December 2013 and replaced ferry service across the river, is now the northernmost border crossing between the two countries.