Mercer Ranch, also known as the famous Campstool Ranch, has been in the Mercer family since the early 1900's.The ranch is in Pinal County, near Mammoth,Arizona.The property spans 15miles lengthwise from the San Pedro River in the west, into the Galiuro Mountains on the east end and consists of just over 32,000 acres of some of the best open range cattle grazing land in the world. The ranch is abundant with water sources:nearly 50 natural springs, 20 dirt stock tanks, 2 solar well pumps with panels, a 71 acre Zimmatic Center Pivot irrigation system, dams, wells and distribution piping support livestock and wildlife over a very large portion of the total 32,000 acres. Water rights have been filed and sustained since 1870. The various wells pump from 3 to 3,000 GPM and there are multiple water storage tanks from 15-10,000 gallon capacity. Approximately 60 miles of 4 and 5 strand barbed wire fence establish border and pasture divisions. Historic sites on the ranch include the two ghost towns of Sombrero Butte and Copper Creek, the old Blue Bird silver mine, the old stage coach stop at Monte Bonito, one of the last pony express routes that ran through the Sombero Butte area and a multitude of old abandoned homesteads. There are three dwellings on the property and a multitude of other outbuildings, corrals, additional storage structures, horse corrals and livestock areas. The property includes a 4200 sqft enclosed metal hangar with multi directional adjoining dirt runways that could be used as an indoor horse facility if desired.The full scope and variability of this property is impossible to describe and must be seen to be understood. The current owner is a 4th generation rancher that grew up on the ranch. The property runs between 500 and 1,000 cattle at a time. The ranch is lush in natural vegetation and with the varied elevation (~2,500'-~6000'), it has very diverse vegetation and wildlife. A small sampling of the vegetation on the property includes Sycamore, Cottonwood, Oak, Juniper, Pinon Pine, Cedar, Palo Verde and Mesquite trees. Cholla, Barrel, Prickly Pear and Sahuaro cacti are abundant. Filaree, Indian Wheat Grass, Mediterranean Grass, Sideoats, Black Grama. Sli, Tridens, Threeawn, Bush Muhly and Burrow grasses are present.There is a 2 bedroom home with 1 and 3/4 bath (remodeled in 2007). The second dwelling is a 16x70 3 bedroom 2 bath Palm Harbor mobile home. The third home is the original 2 bedroom 1 bath adobe ranch headquarters built in the early 1900's, but not currently habitable. OUTBUILDINGS 32x12 mobile office 40x50 commodity grain storage with concrete floor and sides. Mechanical shop Small barn and brick infirmary 40x80 hay barn 40x160 hay barn 30x60 enclosed storage 60x80 enclosed hangar CORRALS Headquarters shipping corrals w/Trutest cattle scale 100x80 covered cattle processing facility 500-head feed lot with shades and feeders 4-5 to 10 acre cattle traps 10 sets of corrals across the ranch at key locations LAND The ranch is fully gated, with access closely controlled and by permission only. 5,991 acres- deeded (71 acres irrigated farmland) 19,984 acres- AZ grazing lease Campstool Allotment #05-2851 2,295 acres- BLM Copper Creek Allotment 3,367 USFS Coronado Copper Creek Permit 240 acres- AZ grazing lease #05-109745-01 702 acres-additional BLM lands Total 32,579 Extensive past successful mining history with strong ore deposits (confirmed via past core samples) show potential mining opportunity on the ranch as well.
RanchProperty Type
1961Year Built
32,000 acresLot Size
Listed by Calvin Case• OMNI Homes International
Listed by Amber Cordova• OMNI Homes International
Bought with Amber Cordova• OMNI Homes International
*Taxable value of land and structures on it ("additions") is determined regularly by local assessors and does not affect market price.
Public record
Beds
—
Baths
—
Stories
1
Lot width
—
Lot depth
—
Lot size
47.17 Acres
Year renovated
—
Sq. Ft.
2,184
Year built
1961
Style
Ranch
County
Pinal County
APN
30705001C
Parking Spaces
—
Basement
—
Accessible
—
HOA Dues
—
Garage
—
Features
—
Last updated by owner on Apr 21, 2026.
Property details
Interior
Bathroom Information
Bathrooms Full: 3
Bathrooms Total Integer: 3
Exterior
Exterior Features
Fencing: Barbed Wire
Land Information
Topography: Rolling
Vegetation: Desert, Grassed, Mesquite
Irrigation Source: Center Pivot, Ditch, Gated Pipe, Side Roll
Lot Information
Lot Size Square Feet: 1,393,920,000
Lot Size Dimensions: Call Agent
Road Surface Type: Gravel
Road Responsibility: Owner Maintenance
Financial
Tax Information
Parcel Number: 307-05-001C
Utilities
Utility Information
Water Source: Pvt Well (Registered), Spring
Sewer: Septic Tank
Location
School Information
Elementary School: Apache
Middle Or Junior School: Mammoth-San Manuel Schools
High School: Mammoth-San Manuel Schools
High School District: Mammoth/San Manuel
Location Information
Directions: Highway 77 past Oracle through Mammoth. Cross the San Pedro river & in 1/2 mile turn south on to River Road. Go approx 6 miles, cross dry creek bed (Copper Creek) Mercer Ranch is 1/2 mile on the righ
UnparsedAddress: 20894 S River Road, Mammoth, AZ 85618
Public facts
Beds: —
Baths: —
Sq. Ft.: 2,184
Stories: 1.0
Lot Size: 47.17 acres
Style: Ranch
Year Built: 1961
Year Renovated: —
County: Pinal County
APN: 30705001C
Home facts updated by county records on Apr 21, 2026
Around this home
Schools
First Avenue Elementary School
Public PreK-6 • Assigned • 6.3mi
5/10
San Manual Jr. High School
Public 6-8 • Assigned • 6.1mi
4/10
San Manuel High School
Public 9-12 • Assigned • 6.1mi
2/10
Provided by GreatSchools
Lifestyle
Provided by Walk Score and Local Logic
Climate risks
1/10 Flood Factor
Minimal risk of a flood reaching the building in the next 30 years
6/10 Fire Factor
10% chance of being in a wildfire in next 30 years
8/10 Heat Factor
7 days above 106° expected this year, 21 days in 30 years
1/10 Wind Factor
Minimal risk of severe winds over next 30 years
1/10 Air Factor
0 unhealthy days expected this year, 0 days in 30 years
Provided by First Street
Historical weather
San Manuel, AZ • 85618
Average low and high temperatures (°F)
60
38
71
46
76
51
78
54
85
61
97
71
97
74
97
74
89
67
85
59
70
45
68
43
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Sun exposure
In this area, properties receive around 13.1 hours in
June and 7.6 hours in December, placing it above the
U.S. average for solar exposure.