The Mittraphap Road or Thailand Route 2 is one of the four major highways in Thailand, along with Phahonyothin Road, Sukhumvit Road, and Phetkasem Road. It runs from Saraburi to Nong Khai. It was built in 1957 with financial assistance from the United States of America and used extensively during the Vietnam War.
In recent times the highway has become congested, particularly in Pak Chong District as it crosses the Dong Phaya Yan Range. Now huge concrete supports are being constructed to carry a multi-lane elevated road through the district to serve the Northeastern provinces and beyond.