When Forward Air Controllers deployed with O-1s to NKP in January 1966, these were the main roads of the Ho Chi Minh Trail with the main traffic entering Laos through the Mu Gia Pass. The two lighter-colored roads crossing the border SE from Mu Gia were not open in January. The one between Hoan Lao and Ban San became Route 137 (in North Vietnam) and Route 912 (in Laos) over the Ban Karai Pass and was discovered by Cricket FACs in April 1966. The next road SW of Dong Hoi was open by 1969 and went through what was known as the Ban Raving Pass.