Final answer:
The dividing line between North and South Korea is the Korean demilitarized zone (DMZ), located along the 38th parallel established after a peace agreement following the Korean War in 1953.
Step-by-step explanation:
The dividing line between North and South Korea is known as the Korean demilitarized zone (DMZ), which is established along the 38th parallel. This line of latitude was selected as the point of division during the post-World War II reconstruction period, where the Soviet Union administered the northern part and the United States administered the southern part of Korea. Following the end of Japanese occupation and a bitter civil war between nationalist and Communist forces, the 38th parallel became the official border after the Korean War in 1953. The peace agreement established the DMZ, which is today the world's most heavily guarded border, with thousands of U.S. soldiers stationed alongside.
To the north of the Korean Peninsula lies China, separated by the Yellow Sea and the Yalu and Tumen Rivers, with Russia along the far northern coast. Japan lies to the east across the Korea Strait. The capital cities of the divided Korea are Pyongyang in the North and Seoul in the South.