It starts from Sunit Right Banner in Inner Mongolia Autonomous Region in the north and ends in Beihai in Guangxi Zhuang Autonomous Region in the south.

National Highway 209 starts from Sunit Right Banner in Inner Mongolia Autonomous Region in the north and ends in Beihai in Guangxi Zhuang Autonomous Region in the south. It is also called the Jiangsu North Line. It passes through counties and cities along the way including Sunit Right Banner and Gegenta. La, Siziwang Banner, Wuchuan County, Hohhot, Horinger, Qingshuihe, Wuzhai, Kelan, Lan County, Fangshan, Lishi, Zhongyang, Jiaokou, Xi County, Daning, Ji County, Hejin, Linyi , Yuncheng, Pinglu, Sanmenxia, ??Lushi, Yunyang District, Shiyan, and Fangxian.

Badong, Jianshi, Enshi, Xuanen, Laifeng, Longshan, Yongshun, Baojing, Huayuan, Jishou, Fenghuang, Mayang, Huaihua, Zhongfang, Hongjiang, Huitong, Jingzhou, Tongdao, Rong'an, Liuzhou, Wuxuan, Lingshan, Hepu, Beihai. The total distance is 3,435 kilometers, passing through 6 provinces: Inner Mongolia, Shanxi, Henan, Hubei, Hunan and Guangxi.

The longest national highway:

The fifth-ranked national highway is the G207 national highway, which generally refers to the Xilin Gol to Xuwen highway, with a total length of 3738km. It starts in Xilingol, Inner Mongolia, passes through Hebei, Shanxi, Henan, Hubei, Hunan, Guangxi, and finally reaches Xuwen, Guangdong.

In fourth place is the G109 national highway, which generally refers to the Beijing-Lhasa highway, referred to as the Beijing-Lhasa line, with a total length of 3922km. It starts in Beijing, passes through Hebei, Shanxi, Inner Mongolia, Ningxia, Gansu, Qinghai, and finally reaches Lhasa, Tibet.

In third place is the G312 national highway, which generally refers to the Shanghai-Horgos highway, referred to as the Hu-Huo line, with a total length of 4967km. It starts in Shanghai, passes through Jiangsu, Anhui, Henan, Hubei, Shaanxi, Ningxia, Gansu, and finally reaches Horgos, Xinjiang.

The second-ranked national highway is the G318 national highway, which generally refers to the Shanghai-Nyalam Highway, referred to as the Shangnyi Line, with a total length of 5,476km. It starts in Shanghai, passes through Jiangsu, Zhejiang, Anhui, Hubei, Chongqing, Sichuan, and finally reaches Nyalam, Tibet.

The first place is the G219 national highway, which generally refers to the Kanas to Dongxing highway, referred to as the Kadong line, with a total length of 10,065km. It starts in Kanas, Xinjiang, passes through Tibet, Yunnan, and finally reaches Dongxing, Guangxi.