Political and physical geography... not always a match

A small observation. Political divisions sometimes trace actual geographic or geological divisions, such as the St. Lawrence and its lakes forming much of the border between Canada and the US in the area. Or the UK occupying a pretty recognizable island province (plus a chunk of someone else's island province, but leave that alone. But often physical geography is not reflected in political division. Oregon and Washington fairly neatly divide into the coastal provinces, where most of the people live (in Oregon the Willamette Valley seaward of the Cascades and a good part of the coastal range; all of this sits atop the geological terrane called Siletzia, which docked with North America about 50 million years ago. The rest of the state is either very mountainous or arid. Same with Washington, where the Sahalish (Puget Sound) basin and the same Siletzia terrane contains most of the people, while the rest of the state is pretty mountainous, sparsely populated, and arid. New Guinea is divided east/west politically into Papua/West Papua (which Indonesia claims, formerly Irian Jaya) on the western half, and Papua New Guinea in the east, an independent nation since 1975. But the geographical division of the island is into a northern and southern province, with the North the collisional (slab failure) mountains formed by the collision of the Australian plate into the Philippine Plate, and the south the portion of the Australian plate that's still colliding.