New Guinea’s Squiggly Border

By the end of the 19th century, the island of New Guinea (the origins of that name can be read at a previous post here) was colonized by three European powers. The Dutch colonized the western portion, the Germans claimed the northeast coast, and the British held the southeast coast adjacent to the colony of Australia. However, the jungles of the island were so thick, and the mountains and valleys in the interior so treacherous, that the colonial interests kept to the coastal fringes. There was little exploration deep into the jungle, and the official border between the territories between the European powers did not need to be properly defined.

After World War I, the British claimed the German territory and the island was then evenly split between the Dutch in the west and the English in the east. Western New Guinea became part of Indonesia when the Dutch possessions gained independence, just as possession of eastern New Guinea (Papua New Guinea, or PNG) passed from England to Australia. Because exploration of the deep interior was limited, the border was only loosely defined as an neat slice down the island.

It was not until 1973 when the land border was finally demarcated. The Indonesian and Australian governments entered into a treaty but which the border would follow the 141st east meridian, cutting neatly down the middle of the island. Looking at the border from a distant view, such as on the left side of the picture above, the border looks perfectly straight—with one small exception. What appears to be a minor deviation on the map is in fact a complicated squiggle when viewed closely, such as on the right side of the picture above.

That is the Fly River, a river that flows mostly through the eastern part of New Guinea but which protrudes slightly to the west of the 141st east meridian longitude line. The impracticality of leaving a minor sliver of land with Indonesia was recognized as the interior was more closely explored, and this territory was ultimately granted to Papua New Guinea. To compensate for this slight gain in territory for PNG, the border south of the Fly River is slightly east of the 141°E longitude line. And another part of this deal was that Indonesia would have the right to use the Fly River to its mouth for navigation to the Ocean.

Such is the logic behind New Guinea’s “squiggly border,” and how a neat compromise can solve potential messy border problems.