Gila and Salt River Meridian
Encyclopedia
The Gila and Salt River Meridian intersects the base line on the south side of Gila River
, opposite the mouth of Salt River
, in latitude 33° 22' 40" north, longitude 112° 17' 25" west from Greenwich, and governs the surveys in the territory of Arizona
. The initial point is located on "Monument Hill", an easily visible hill just south of the confluence of the Gila and Salt Rivers, in Avondale, Arizona
, about 14 miles (23 kilometers) southwest of downtown Phoenix
. The original marker has been lost for many years, but a brass plaque was mounted in rock in 1931 (due to damage of the plaque, this could be 1961), then a large concrete, brass and aluminum monument was constructed about 14.8 feet (4.5 m) (center-to-center) from the 1931 marker. That monument was, in turn, modified in 2006. The location was added to the National Register of Historic Places
(listing #02001137) as of October 15, 2002, but apparently the plaque for that listing was constructed on the summit at the same time as the 2006 modification of the nearby monument.
For the 1984/2006 marker, hand held GPS units give a reading of 33° 22.631' N Latitude and 112° 18.366' W Longitude due to the specific geoid
used. The angle between the 1984/2006 marker and the 1931 marker is at a compass heading of 292°, aka 22° north of due west. The location is immediately east of Phoenix International Raceway
and the western side of Monument Hill is terraced for low-priced race viewing. See External links for further details.
Gila River
The Gila River is a tributary of the Colorado River, 650 miles long, in the southwestern states of New Mexico and Arizona.-Description:...
, opposite the mouth of Salt River
Salt River (Arizona)
The Salt River is a stream in the U.S. state of Arizona. It is the largest tributary of the Gila River. The river is about long. Its drainage basin is about large. The longest of the Salt River's many tributaries is the Verde River...
, in latitude 33° 22' 40" north, longitude 112° 17' 25" west from Greenwich, and governs the surveys in the territory of Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. The initial point is located on "Monument Hill", an easily visible hill just south of the confluence of the Gila and Salt Rivers, in Avondale, Arizona
Avondale, Arizona
Avondale is a city in Maricopa County, Arizona, USA, adjacent to Phoenix, Arizona. According to 2010 Census Bureau, the population of the city is 76,238.Avondale is the home of Phoenix International Raceway, an auto racing facility...
, about 14 miles (23 kilometers) southwest of downtown Phoenix
Phoenix, Arizona
Phoenix is the capital, and largest city, of the U.S. state of Arizona, as well as the sixth most populated city in the United States. Phoenix is home to 1,445,632 people according to the official 2010 U.S. Census Bureau data...
. The original marker has been lost for many years, but a brass plaque was mounted in rock in 1931 (due to damage of the plaque, this could be 1961), then a large concrete, brass and aluminum monument was constructed about 14.8 feet (4.5 m) (center-to-center) from the 1931 marker. That monument was, in turn, modified in 2006. The location was added to the National Register of Historic Places
National Register of Historic Places
The National Register of Historic Places is the United States government's official list of districts, sites, buildings, structures, and objects deemed worthy of preservation...
(listing #02001137) as of October 15, 2002, but apparently the plaque for that listing was constructed on the summit at the same time as the 2006 modification of the nearby monument.
For the 1984/2006 marker, hand held GPS units give a reading of 33° 22.631' N Latitude and 112° 18.366' W Longitude due to the specific geoid
Geoid
The geoid is that equipotential surface which would coincide exactly with the mean ocean surface of the Earth, if the oceans were in equilibrium, at rest , and extended through the continents . According to C.F...
used. The angle between the 1984/2006 marker and the 1931 marker is at a compass heading of 292°, aka 22° north of due west. The location is immediately east of Phoenix International Raceway
Phoenix International Raceway
Phoenix International Raceway, also known as PIR, is a one-mile, low-banked tri-oval race track located in Avondale, Arizona. The track opened in 1964 and currently hosts two NASCAR race weekends annually. PIR has also hosted the Indycar Series, CART, USAC and the Rolex Sports Car Series...
and the western side of Monument Hill is terraced for low-priced race viewing. See External links for further details.