Unless you are a follower of that peculiar sub-cult of Civ III fanaticism that, considers the optimum opening to be: taking the starting worker and settler hut hunting and razing the civilized world to the ground with the force of mighty conscript warrior hoard, you have undoubtedly noticed the subtle power of cultural borders. That power is manifested in many forms: the ability to restrict road use, the ability to work tiles, the ability to utilize resources, and the ability to subvert neighbors. This paper will concern itself with the ability to predict cultural borders from first principles, namely city placement and city culture. Many of us have no doubt wondered, as our capital approaches the 20k threshold, why the border of the near by AI city, which contains only a temple, has not collapsed in the face of our omnipotent glow. The basic flaw in our logic is how we approach the problem. It is misleading to think of borders pushing on borders; it is instructive to think tile by tile. I. When a city's culture reaches its nth threshold value, it gains the ability to place claims of rank n+1 on all tiles at a distance n+1. (Note: threshold values are of the form 10^n c.p.) eg: When you found you first city, it has undergone 0 expansions so it places claims rank 1 on tiles distance 1. After then turns culture reaches its first threshold value, and in addition to its rank 1 claim it plants rank 2 claims in the tiles distance 2 from it. II. Ocean tiles may only hold claims of rank 2. III. Each tile is assigned to the civ that controls the city that has the lowest rank claim on it. IV. In the event that multiple cities have claims of the same rank on a tile, the tile is assigned to the competing city with the largest culture. V. In the event that multiple cities have claims of the same rank on a tile and those cities have equal culture, it goes to the older city. VI. In the event that multiple cities have claims of the same rank on a tile, those cities have equal culture, and they were founded the same year, the tile looks N, NW, W, SW, and S in order and assigns itself to the first of the competing cities it finds in this way. VII. If an unassigned tile finds a tile of a single civ directly adjacent to both the NW and SE, it is assigned to that civ. VIII. If an unassigned tile finds a tile of a single civ directly adjacent to both the NE and SW, it is assigned to that civ.