The New Mexico Territory was organized as a U.S. territory in 1850, and for many years its precise boundaries and internal administration remained undefined. In 1853, the territory was expanded south of the Gila River in the Gadsden Purchase. Proposals for a division of the territory and the organization of a separate Territory of Arizona were advanced as early as 1856. The first proposals for a separate Arizona Territory were not based on the modern east–west division but rather a north–south division. These proposals arose from concerns about the effectiveness of the territorial government in Santa Fe to administer the newly acquired southern portions of the territory.