The American wild horse, often called a Mustang, is a free-roaming animal descended from horses brought to the Americas by Spanish explorers centuries ago. These horses are technically considered feral because their ancestors were once domesticated, distinguishing them from truly wild species. They hold a unique place in the country’s history, having been declared “living symbols of the historic and pioneer spirit of the West” by the United States Congress in 1971. The focus of their protection and management is their current distribution across the American West, where they reside primarily on federally administered lands.
Primary Geographic Range
The vast majority of the country’s free-roaming wild horse population is concentrated in 10 Western states, inhabiting the expansive public rangelands managed by the federal government. These herds are found within designated areas known as Herd Management Areas (HMAs).
The distribution of these animals is heavily skewed toward a few states, with the arid and semi-arid landscapes of the Great Basin providing the most extensive habitat. Nevada holds the largest population by a significant margin, containing more than half of the entire free-roaming census. Following Nevada, the states of Wyoming and Utah also host substantial populations, with thousands of horses roaming within their respective HMAs.
Oregon, California, and Idaho are the next states in order of population density, all supporting sizable herds on their federal lands. These HMAs are spread across approximately 27 million acres of public land in the West, with the horses often navigating a complex checkerboard of federal and private land ownership. This geographical confinement means that the herds are subject to the carrying capacity of the land, which is often limited by forage and water availability, particularly in drought conditions. The remaining population is distributed across Arizona, Colorado, Montana, and New Mexico.
Legal Status and Federal Management
The legal status of these animals is defined by the Wild Free-Roaming Horses and Burros Act of 1971, which mandates their protection and management on public lands. This federal law established that the horses and burros are to be treated as an integral part of the natural system of the public lands where they were found at the time of the Act’s passage. The Act makes it a federal offense to harass, capture, or kill these animals on federal property.
Operational responsibility for implementing this Act falls primarily to the Bureau of Land Management (BLM), which oversees the majority of the HMAs. The U.S. Forest Service (USFS) manages a smaller number of territories that fall within National Forest boundaries. Both agencies are directed to manage the herds in a way that maintains a “thriving natural ecological balance” on the rangelands.
This management duty requires the agencies to balance the well-being of the herds with the health and productivity of the public lands, which are also used for wildlife habitat, livestock grazing, and recreation. The agencies’ duties on the range include monitoring herd health, assessing rangeland conditions, and determining the appropriate population levels for each HMA.
Off-Range Holding Facilities
Wild horses removed from their HMAs do not leave federal jurisdiction but are instead transferred to off-range holding facilities, which are geographically distinct from their native rangelands. The BLM maintains two types of facilities to house these animals: short-term corrals and long-term pastures. This system is necessary because the number of horses removed from the range far exceeds the demand for adoption by private individuals.
Short-term corrals function as temporary holding centers, often resembling large feedlots, where horses are first taken following a gather operation. Here, the horses are prepared for the adoption or sale program, undergoing veterinary checks, vaccinations, and freeze-marking for identification. These corrals are more expensive to operate due to the intensive care and feeding required.
Animals that are not adopted or sold within a certain timeframe are moved to long-term pastures. These are generally large, private tracts of land contracted by the BLM, often located in states like Oklahoma and Kansas. These pastures allow the horses more space and a free-roaming environment for the rest of their lives, providing a less costly option for lifetime care.
Population Dynamics and Counts
The management challenge for wild horses stems from the disparity between the number of animals on the range and the established Appropriate Management Level (AML). AML represents the population range that the BLM determines can be supported without causing deterioration to the rangeland or negatively impacting other resources and uses. The nationwide AML for horses and burros is set at a maximum of about 26,785 animals.
The estimated on-range population of wild horses and burros was approximately 73,520 as of March 1, 2024, meaning the actual population is nearly three times the established AML. This excess population is a result of the horses’ high reproductive rate, which can allow herds to double in size roughly every four years, largely due to the absence of natural predators. The difference between the actual population and the AML is the primary driver for management actions, particularly the removal of excess animals from the range.
The consequence of these removals is the substantial off-range population, which totaled about 68,000 animals in holding facilities as of Fiscal Year 2024. This captive population grows as the number of animals gathered and removed consistently exceeds the number placed into private care through adoption or sale. The need to care for this large and expanding population, both on and off the range, drives the continuing discussion over sustainable management strategies.