Zhangjiakou was historically known to the Europeans as Kalgan until the mid 20th century. This name derives from the Mongolian name of the city, (Čiɣulaltu qaɣalɣa) or, shorter, (Qaɣalɣan), where the Qaɣalɣa[n] means "gate" (in the Great Wall). In Manchu, the city is known as (Imiyangga jase).
Zhangjiakou has been nicknamed "Beijing's Northern Door" due to its strategic location.
The city lies in the northwestern corner of the province and is linked from Datong in Shanxi by the Xuanda Expressway and from Beijing by means of the Jingzhang Expressway. Zhangjiakou is further linked by a freeway to Inner Mongolia which opened on September 7, 2005.
The water-scarce city was historically the chief northern gate in the Great Wall to China for Europeans travelling along the Tea Road (such as Nicolae Milescu).
In the 19th century, the town was the seat of a very extensive transit trade. In early autumn long lines of camels would come in from all quarters for the conveyance of the tea chests from Zhangjiakou, the Kalgan, to Kyakhta; and each caravan usually made three journeys in the winter. Some Russian merchants had permanent residences and warehouses just outside the gate.
In October 1909, Kalgan was connected by railway with Peking. The 1911 Encyclopaedia Britannica noted that, in Kalgan, "the ordinary houses have an unusual appearance, from the fact that they are mostly roofed with earth and become covered with green-sward" and that "on the way to Peking the road passes over a beautiful bridge of seven arches, ornamented with marble figures of animals".
In the early 1960s at the height of Sino-Soviet tensions, Zhangjiakou was considered one of the most important cities in China for military strategy reasons. Zhangjiakou was aptly nicknamed, "Beijing's Northern Door", because whoever controlled Zhangjiakou was in a good position to either attack (in the case of the Soviets) or defend (in the case of the Chinese) Beijing.
The vicinity of Zhangjiakou is rich in coal and iron ore, making it an ideal location for developing iron and steel industry. Apart from metallurgy, the city is home to one of China's most important grape wine industries, with the Great Wall Wine Company being located in Shacheng (沙城镇), Huailai County. 
Zhangjiakou is home to Hebei North University.