It is the first highway in Thailand to meet international standards, and the first highway in Thailand to use both asphalt and concrete. It received the name "Thanon Mittraphap" on February 20, 1957. The name literally means "Friendship Road". It is the main road that connects Isan (northeastern Thailand) to Saraburi. It passes through the provinces of Nakhon Ratchasima, Khon Kaen, Udon Thani, and ends in Nong Khai, where it links with the Thai-Lao Friendship Bridge to Laos (subsidised by Australia government).