The Kabul–Kandahar Highway is a road linking Afghanistan's two largest cities, Kabul and Kandahar. This highway is a key portion of Afghanistan's national road system or "Ring Road". The entire highway from Kandahar to Kabul is on flat surface, with no mountain passes. Approximately 35 percent of Afghanistan's population lives within 50 kilometers of the Kabul to Kandahar portion of the Ring Road.