History In 1906, the RGLIG performed an unauthorized separation of the Rio Grande , which moved a 413-acre piece of land, including Rio Rico, south of the river. The company was later fined, but the separation of the river was allowed to stand if the company placed boundary markers, which it never did.
The land was now physically south of the Rio Grande the border between Mexico and the U.S. Mexican authorities not knowingly got control of the area, which became known as the Horcón Tract. However, since the course change was due to man-made changes and not natural changes, international law dictated that the land remained US territory, a fact that was not in dispute. Something of a resort town grew up there during the 1920s and 1930s, with free-flowing liquor and gambling.
Right now it currently belongs to the US and part of Texas.