The segment called National Route 9A begins at Đông Hà and ends at Lao Bảo on the Vietnam-Laos border and is entirely within Quảng Trị Province.

The 8 km-long segment called National Route 9B begins at Dong Ha and runs eastward to Cửa Việt Port.

The road was built to connect the towns along the Mekong River in present-day Laos over the Annamite Range to the Vietnamese coast.

In recent years with the implementation of Vietnam's Doi Moi reforms there has been an increase in cross-border trade with Laos and Route 9 has been progressively upgraded.

As route AH16 in Asian Highway Network, the road continues westwards through Laos and across the Mekong into Thailand.