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The Arizona Initial Point Bartlett's Surveyors, led by Lieutenant Amiel Weeks Whipple, in charge of the Astronomical Survey, and A. B. Gray, in charge of the topographical survey, began their work in New Mexico, first working on the new International Boundary between the Rio Grande and the Gila River, then surveying the Gila River across Arizona. A Mexican Boundary Commission crew, led by Francisco Jimenez, was also surveying the Gila River at the same time. The American team began the Arizona section of the survey near Safford and worked their way west along the Gila River. In November of 1851 they were at the Pima Villages south of present-day Phoenix. When they reached the confluence of the Gila and Salt Rivers, Whipple found a monument already built on a hill on the Mexican side by Jimenez' team. Whipple connected his astronomical survey with this monument. In 1865 this point was chosen as Arizona's Initial Point.
The original monument is described as being six feet high and eight feet around at the bottom, tapering to four feet at the top. There was a pole extending 8 feet above that, bringing the total height to fourteen feet. The original monument has long since been destroyed by vandals and was replaced in 1984 by the present concrete one. Since there are no pictures of the original that I know of, I show here a drawing of a typical monument from W.H. Emory's United States and Mexican Boundary Survey of 1857 which surveyed and marked the new international boundary established by the Gadsden Purchase. The modern photograph shows the monument in January 2002, looking toward downtown Phoenix. Bartlett Locations: Expeditions & Information: |
The
Initial Point, located on a hill at the north end of the Sierra Estrella
Mountains near the confluence of the Salt and Gila Rivers, is the point
of reference that most land in Arizona is surveyed from. This hill is
now on the grounds of the Phoenix International Raceway. From the
Initial Point
east and west extends the "Gila and Salt River Baseline" (now
the alignment of Baseline Road), and the north-south "Gila and Salt
River Meridian" (along 115th Avenue). From this point the land is
divided into 6-mile square townships which are subdivided into 36
one-square-mile sections. Each township is identified by its position
relative to the initial point, for example the first township northeast
of the initial point is "Township 1 North, Range 1 East" or
T1N, R1E.