The Initial Point for the survey of Arizona lies atop a 150-foot tall hill west of Phoenix called Monument Hill. This site was selected as it has a good view and is visible from around the area, and because it lies next to a major regional geographic feature, the confluence of the Gila River and the larger Salt River. The site was originally surveyed and marked with an eight-foot tall rock monument in 1851, as part of the U.S./Mexico boundary survey. So when the field work for the territorial survey was started in 1865, this made a solid, already-established point to base it from. An early version of the current monument was made in 1984, during the first annual “National Surveyors Week” by several entities working together, including the BLM, the Gila River Indian Community, and the local chapter of the Arizona Professional Land Surveyors. The monument has been vandalized and repaired a few times since then, including a major restoration in 2006, which rebuilt the concrete cross with the tile inlay.
Looking west from the Initial Point along the baseline, downstream along the Salt River (which carries effluent away from Phoenix) past the Phoenix International Raceway track.
Looking east into the Gila River Indian Reservation, the baseline is visible on the ground as it becomes Baseline Road. Downtown Phoenix is in the distance on the left.
Looking north over the confluence of the Gila and Salt Rivers, the meridian extends to the horizon as 115th Avenue.
Looking south, the meridian is the boundary between the Gila River Indian Reservation and county park land.
All of Arizona, except a portion of the Navajo Reservation (in red) was surveyed from this point.