Who was the first dictator of North Korea and over time how did Korea split to north and south.

The first dictator of North Korea was Kim Il-Sung. The split was when the Japanese empire was dismantled at the end of WWII. Korea became part of the Cold War. It was divided into two "spheres". With America's influence in the south and Russia's communist regime in the north.  

the border between arizona and new mexico is a thin, black line; this indicates a state boundary.

its correct: it's a thin line, and it's a state boundary, correct