Zeihan provides the most comprehensive overview of world topography and demographics I've seen in a modern book on world evolution. He boils down world progress to: defensible borders and a large number of rivers. River trade is 1/17th the cost of land trade so those with large rivers plus defensible borders became powerful and no political structure or ideology matters as much as natural resources. The US has > 20,000 miles of navigable rivers and no other country has more than 2,000 miles and the US is surrounded by natural defenses (two oceans) and water attacks are infinitely harder. He explores shale oil, country demographic impacts and the likely political futures based on this.
The Full Ratchet