The 37th parallel north is not a border in the traditional sense, as it does not mark a political boundary between two countries. However, it does pass through several countries and geographical features, including:

* United States: It runs through several states, including Virginia, North Carolina, Tennessee, Kentucky, Missouri, Kansas, Oklahoma, Texas, and California.

* Mexico: It crosses through the northern states of Sonora and Chihuahua.

* China: It passes through several provinces, including Gansu, Shaanxi, Shanxi, Henan, Anhui, and Jiangsu.

* North Korea: It crosses through the northern part of the country.

* South Korea: It crosses through the southern part of the country.

* Japan: It passes through the southern island of Kyushu.

* Algeria: It crosses through the northern part of the country.

* Tunisia: It crosses through the northern part of the country.

Therefore, it is more accurate to say that the 37th parallel north runs through several countries and geographical features, rather than forming a border.