The particulars of the Adams-Onís Treaty, it turns out, were greatly aided by a map that was produced by one John Melish, a traveler, merchant, author, and cartographer of Scottish origin who ended up being the first mapmaker to create a coast-to-coast charting of the United States. But Melish also is known in the annals of history for a cartographical blunder that both misplaced the 100
th meridian by a hundred or so miles to the east and failed to recognize the seemingly obvious fact that the Red River, in the general vicinity of the 100
th meridian, is split into multiple forks: the North Fork, the Elm Fork, the Salt Fork, and the southern Prairie Dog Town Fork. (For those who are not currently looking at a map, the region in question is roughly where the Texas Panhandle’s vertical, eastern border with Oklahoma intersects with the somewhat horizontal portion of the Texas-Oklahoma border that is more or less traced by the Red River.)