Kelvin is an

unincorporated community An unincorporated area is a parcel of land that is not governed by a local general-purpose municipal corporation. (At p. 178.) They may be governed or serviced by an encompassing unit (such as a county) or another branch of the state (such as th ...

Pinal County Pinal County is a county in the central part of the U.S. state of Arizona. According to the 2020 census, the population of the county was 425,264, making it Arizona's third-most populous county. The county seat is Florence. The county was est ...

Arizona Arizona is a U.S. state, state in the Southwestern United States, Southwestern region of the United States, sharing the Four Corners region of the western United States with Colorado, New Mexico, and Utah. It also borders Nevada to the nort ...

, United States. Kelvin is located near the

Gila River The Gila River (; O'odham ima Keli Akimel or simply Akimel, Quechan: Haa Siʼil, Maricopa language: Xiil) is a tributary of the Colorado River flowing through New Mexico and Arizona in the United States. The river drains an arid watershed of ...

, east-northeast of

Florence Florence ( ; ) is the capital city of the Italy, Italian region of Tuscany. It is also the most populated city in Tuscany, with 362,353 inhabitants, and 989,460 in Metropolitan City of Florence, its metropolitan province as of 2025. Florence ...

. The community was founded on the north side of the Gila River across from the Riverside Stage Stop that sat on the south side of the Gila, where the town of Riverside still exists. The town was named Kelvin, after Kelvin Grove in

Scotland Scotland is a Countries of the United Kingdom, country that is part of the United Kingdom. It contains nearly one-third of the United Kingdom's land area, consisting of the northern part of the island of Great Britain and more than 790 adjac ...

, in 1900. The railroad company later founded Ray Junction immediately north of the Kelvin Bridge on account of the development of

Ray, Arizona Ray is a ghost town in Pinal County, Arizona, United States; it is mostly known for the large copper mine there. It was named after the nearby Ray mine, which was begun by the Ray Copper Company in 1882, after the sister of one of the miners, w ...

, and it was the place where the railroad branched from the main line of the

Arizona Eastern Railway The Arizona Eastern Railway is a Class III railroad that operates of railroad between Clifton, Arizona, and Miami, Arizona, in the United States. This includes trackage rights over the Union Pacific Railroad between Lordsburg, New Mexico, and ...

heading up to the

Ray mine The Ray mine is a large copper mine in Pinal County, Arizona, near the town of Kearny, in the southwestern United States. ASARCO, a subsidiary of Grupo México, currently owns the mine, which it acquired from Kennecott Copper in 1986. The Ray ...

. The post office and original old west town site retained the name of Kelvin. This group of small communities are all located within a two-mile circumference from each other and many of the old foundations of Kelvin's original town site still exist. The ruins of the massive mill are still plainly visible. The ruins of the adobe post office are still partly standing near the junction of the Florence / Kelvin Highway and Ray Road. The

Kelvin Bridge A Kelvin bridge, also called a Kelvin double bridge and in some countries a Thomson bridge, is a measuring instrument used to measure unknown Resistor, electrical resistors below 1 ohm. It is specifically designed to measure resistors that a ...

and the Mineral Creek Bridge, which are listed on the

National Register of Historic Places The National Register of Historic Places (NRHP) is the Federal government of the United States, United States federal government's official United States National Register of Historic Places listings, list of sites, buildings, structures, Hist ...

, are located near Kelvin.

References

{{authority control Unincorporated communities in Pinal County, Arizona Unincorporated communities in Arizona