The Sky Islands Odyssey is a network of bikepacking routes that offer a journey through the culturally rich, biodiverse, and complex borderlands of Southern Arizona, featuring a fun network of dirt, rocky, and sandy roads that traverse the ever-changing landscapes characteristic of the Sky Islands bioregion of the Sonoran Desert. These routes earn their name from the biological wonderland known as the Sky Islands, which extends from southeast Arizona to northern Mexico.

With three main route options and several alternates in Sky Islands Odyssey network, there is something for everyone. In addition, due to popular demand, gravel bike-friendlier versions of the East Loop and the Full Loop are also now available. Ranging in distances from 125 to 235 miles, the three routes are designed so that you can enjoy the Sky Islands Odyssey in two separate parts or one complete loop, depending on how much time you have. Each route tells a story of flora and fauna, history, and the human and wildlife consequences of U.S. immigration policies.

History and Backstory

This region has a long history of Spanish, Mexican, and American land colonization and human migration dating back to the late 1770s, when Spanish conquistadors used the region as an expedition route to colonize the indigenous lands of present day San Francisco and sequentially New Spain, which included much of the land in what is today the Western United States. Under the Mexican Cession in 1848, Arizona became a territory of the United States, spurring an influx of miners traveling west for the California Gold Rush to settle in the region. Today, this region continues to make history every day as border-crossing corridor at the center of debate of US immigration policies, border patrol, and a humanitarian crisis. While this aspect of the route may deter some, for others is offers a unique, humanizing perspective of a very current issue in U.S. history.

Ancestral Lands

The Sky Islands Odyssey routes travel through the ancestral lands of the Tohono O’odham, Chiricahua Apache, and Ópata. Baboquivari Peak, a significant visual landmark on the West Loop, Full Loop, and west side of the East Loop, is the most sacred place to the Tohono O’odham as it is the birthplace of their creator, I’itoi and the center of their cosmology. Tohono O’odham is pronounced, Thaw-(haw)-naw Awe-(awe)-thumb, or Thaw-naw Awe-thumb. Tohono means desert and O’odham means people. To this day, the Tohono O’odham Nation plays a significant, active, and essential role in state and federal politics and in protecting land, water, and human rights in southern Arizona. With approximately 36,000 enrolled members, and a reservation of more than 2.5 million acres of southern Arizona land (the size of the state of Connecticut), the Tohono O’odham Nation is the second largest indigenous land holding in the United States.


Fossils dating back to the Late Pleistocene Period prove that plant and animal communities were not the same as they are today. Remains of several large animals that are now extinct have been unearthed at several sites in the San Pedro River Valley and other places in Arizona and the Southwest.

During this period, the broad plains of the San Pedro River Valley teemed with larger herbivores such as camels, llamas, horses, mastodons, mammoths, and long-horned bison, as well as tapirs and ground sloths. These large animals were preyed upon by the dire wolf, jaguar, lion, cheetah, cougar, bear, and humans. Most of these large Ice Age mammals, collectively called megafauna by scientists, are now extinct.

Scientists do not fully understand why many megafauna species became extinct while others, such as the grizzly and black bear, cougar, elk, pronghorn, and wolf, survived this period. Human predation, climate, vegetation changes, or a combination of these factors may have caused such selective extinctions.

Human History

The first Homo sapiens appeared in North America in 10,000 BCE, following herds of big-game animals migrating from Asia across the Bering land bridge. They eventually made their way into every habitat on the North American continent.

Archeological evidence recovered from six sites in the San Pedro Valley, where Ice Age hunters killed mammoth and bison, indicates that people belonging to the Clovis culture were roaming southeastern Arizona at least 11,000 years ago.

The most commonly held perspective on the end of the Clovis culture is that a decline in the availability of megafauna, combined with an overall increase in a less mobile population, led to local differentiation of lithic and cultural traditions across the Americas.

The Clovis people were replaced by a succession of cultures such as the Cochise, Preceramic O’otam, the Formative O’otam (Pima), Hohokam, and the Sobaipuri dependent on small game, the gathering of seeds and nuts, and later, agriculture. Land occupancy of these groups overlapped with the arrival of Spanish explorers such as Fray Marcos de Niza, Francisco Vasquez de Coronado, Padre Eusebio Kino, and Captain Juan Mateo Manje.

Chiricahua Apache moved into the area east of the Santa Rita Mountains in approximately 1680 CE and had largely replaced the indigenous tribes by the end of the 17th century. The Apaches and their allies, plus the introduced disease, malaria, kept settlement by those of European descent at low levels until the 1870s.

Numerous archeological sites are recorded in the Arizona State Museum field surveys and the Amerindian Foundation for the upper San Pedro and Babocomari Drainages, as well as in the Santa Rita and Patagonia Mountains.

History of Domestic Livestock Grazing and Its Impact on the Land

The archeological record suggests that bison, North America’s principal large grazing mammal, were uncommon in southeast Arizona or perhaps missing altogether after the end of the last ice age. Spanish and Mexican colonizers slowly introduced the first large hoofed grazers throughout the seventeenth, eighteenth, and early nineteenth centuries. However, domestic livestock was not thought to impact the landscape under their rule significantly. The Gadsden Purchase of 1853/54 transferred ownership from Mexico to the United States, but relatively little changed regarding the management of the land until after the Civil War when the combined efforts of the American military and westward migration of Americans enabled the development of a large livestock industry.

A combination of factors, including ignorance of the climate and ecology of the region, led to a series of overgrazing events, as well as a period of severe drought in the late nineteenth and early twentieth centuries which resulted in the loss of topsoil, changes in hydrology, and the realization that grasslands of the Southwest present unique challenges to ranchers. Because these grasslands survived and evolved without the presence of native hoofed grazers for 10,000 years or more, they were unprepared for the introduction of domestic grazers at such a large scale. As a result, very arid grasslands in the Southwest were converted to desert scrublands by grazing and are permanently incapable of supporting grasses today.

Much of the modern management of the existing grassland prairies has sought to strike a balance between the economic necessities associated with ranching on a landscape with little or no natural defenses against grazing by domestic livestock.

Borders and Human Migration

The reality of coming face-to-face with the issues at the borderlands is not what many want to be exposed to when we are on a cycling vacation from work, rain, or snow back home. However, the humanitarian crisis in this region is a reality nonetheless. While cyclists will never understand what it is like to cross the border this way, we travel through the same landscape under human power. Find a historical perspective below as well as further details and resources on the subject…

A Brief History of Borders

The concept of borders has always been abstract in this region. For thousands of years, the Tohono O’odham inhabited this region and a much larger area called Papagueria, which extended south to Sonora, Mexico, north to Central Arizona, west to the Gulf of California, and east to the San Pedro River. In the late 1770s, Spanish conquistadors used this region as an expedition route to colonize the indigenous lands of present-day San Francisco, California, and, sequentially, New Spain, which included much of the land of what is today the Western United States. The Mexican War of Independence resulted in the transfer of New Spain to Mexican rule in 1821. In 1848, after the Mexican-American war and the Treaty of Guadalupe Hidalgo, the U.S. claimed the territory as its own. The Gadsden Purchase of 1854 secured more land from Mexico, which is now present-day southern Arizona and southern New Mexico, for the development of the transcontinental railroad. After the Gadsden Purchase, the Tohono O’odham land was divided in half. The Tohono O’odham continued to lose their land as treaty promises were disregarded in favor of the growing demand for Euro-American settlement for mining, cattle ranching, and the development of the transcontinental railroad.

Humanitarian Crisis

Just as it is today, human migration in this region has always been part of its history. Sadly, however, due to the U.S. immigration policy, “Prevention Through Deterrence,” this region has become the location of a humanitarian crisis. The policy is designed to discourage people from crossing the U.S./Mexico border near urban areas and force them to cross more remote and unpopulated regions, where the natural environment would act as a deterrent. The expectation is that the difficulties people will experience while traveling through the harsh climate of the Sonoran Desert will ultimately discourage people from making the journey. Unfortunately, this strategy failed to deter people from crossing the border, and instead, six million people have attempted to migrate through the Sonoran desert since 2000. At least 7,505 people have died in the U.S./Mexico borderlands in the 20 years between 1998 and 2018, mainly from dehydration, hyperthermia, or heat exhaustion while attempting this journey. It is expected that the number of deaths in the desert is far higher due to the number of deaths that go uncounted and unrecorded. In 2021 in Pima County alone (the county the SIO routes travel through), the nonprofit Humane Borders and the Pima County Medical Examiner’s office found the remains of 43 people in June and the remains of a total of 127 people in the first half of the year, an increase over 2020.The most obvious evidence of this border-crossing corridor is the presence of Border Patrol. In some regions of the route, particularly in the south and west, border patrol agents will be the only people/vehicles you will see for days. These officers are on patrol for migrants and are unfazed by the presence of bicycles. There are also northbound border patrol checkpoints on State Highway 83 and Interstate I-19 that you will go through if you drive to and from the route. These checkpoint officers are looking for human trafficking. In recent years, border patrol has expanded its use of drones and surveillance towers throughout the region. Subtle things you may notice in the southern and western portions of the route are tire draggers on the side of the road, which is a method used by Border Patrol to groom the dirt roads so they can track new footprints. Lastly, you may notice clothing and personal belongings left behind on the side of the road or in the bushes.

In recent years, Executive Order 13767 was created by former president Trump as an emergency order to bypass environmental protections to rush further construction of the U.S. border wall across southeastern Arizona. The construction of this new section of wall has created new roads through wilderness areas, blown up mountains, and blocked essential animal migration corridors for threatened and endangered species (and all mammals larger than 6″ wide).

The amount of suffering in the borderlands is not what some folks want to be confronted with when they are on a cycling vacation from work, rain, or snow back home. However, this humanitarian crisis in the borderlands is a reality nonetheless. While cyclists will never understand what it is like to cross the border this way, we travel through the same landscape under human power. Perhaps riding one of the Sky Islands loops, experiencing the harsh environment, and witnessing the militarization can bring us closer to empathy and compassion for those who cross. Of course, you may leave this place with more questions than answers. Still, you will gain a unique and critical perspective on a massive and urgent issue in which we should all be invested.

If you feel compelled to help the humanitarian crisis in the borderlands in any way, please consider donating or volunteering to No More Deaths. No More Deaths aims to end death and suffering in the Mexico–US borderlands through civil initiative: people of conscience working openly and in community to uphold fundamental human rights. Their work embraces the Faith-Based Principles for Immigration Reform and focuses on the following themes:

  • Direct aid that extends the right to provide humanitarian assistance
  • Witnessing and responding
  • Consciousness-raising
  • Global movement building
  • Encouraging humane immigration policy

Similarly, consider donating to or volunteering for Indivisible Tohono, Borderlands Restoration Network, and the Sky Islands Alliance to support indigenous communities and conservation in the region.

Guidelines for Humanitarian Aid / Migrant Encounters

This region is a popular border-crossing corridor for asylum seekers and migrants. As people recreating in the borderlands, you will unlikely encounter asylum seekers and migrants because they are often afraid and don’t know if you are there to help or turn them in. If you come face-to-face with a migrant, it’s usually because they are debilitated and have decided they can’t go on or need medical attention. While every encounter is different, here are some guidelines:

  • It is legal and appropriate to give migrants water, food, first aid for minor injuries, and a blanket or clothing. In addition, if a migrant asks you to get in touch with a friend or a relative to let them know what has happened to them and their situation, you may do so.
  • As autonomous human beings, migrants have the right to make their own decisions, even if they seem ill-advised or unlawful. However, you can not intentionally help migrants engage in any illegal course of conduct– for example, by giving them rides to the home of a friend or relative or assisting them to avoid capture by law enforcement, even if that may seem morally or ethically acceptable under the totality of the circumstances.
  • You have no obligation to turn migrants into law enforcement unless they request your help to do so.
  • If you encounter a migrant who is in dire need of emergency medical treatment or seems to be near death, you should immediately call 911 or the border patrol (877-227-5511) for help using a cell phone or SOS. If the situation is grave and there is no cell signal, you may give the affected migrant a ride to the nearest border patrol checkpoint or a hospital. In such a case, you should call the border patrol and report what has happened at the earliest reasonable opportunity.


Border Wall

Humanitarian Crisis

Biological Wonderland

The region comprises 65 isolated mountain ranges covered in oaks and pines that rise like an archipelago from a sea of desert and grassland. In the Sky Islands, plants and animals from several major biological zones converge; the Chihuahuan and Sonoran deserts, the Colorado Plateau and the Rocky Mountains, and the Sierra Madre Occidental resulting in half of the world’s biomes represented in a relatively small geographic area. More than half the entire bird species of North America migrate to the Sky Islands. In addition, more than a third of all snake species in the U.S. are here; an estimation of 100 mammals, 150,000 invertebrate (insect) species, evidence suggesting the highest diversity of bees than anywhere else in the world, and the only place in the U.S. where jaguars still roam.

“El Jefe” the Jaguar

Jaguars once existed throughout northern Mexico and the southern United States. However, due to habitat loss, poaching, and human-wildlife conflict, jaguars have been eliminated from the U.S. They have been listed as endangered under the U.S. Endangered Species Act since 1997 and near threatened by IUCN Red List since 2002. Jaguars are the largest cat species in the Western Hemisphere, and as apex predators, they play an essential role in the ecosystem and regulate prey populations. In addition, these majestic creatures have been prominent mythological symbols of indigenous cultures of the Americas, including those of the Pueblo, Aztec, Mayan, and Incan civilizations. Historically, their natural habitat has ranged from northern Argentina to the Grand Canyon in the U.S. Southwest.El Jefe, “the boss,” is the name of a male jaguar that roamed southern Arizona’s Santa Rita Mountains from 2011-2015. For years, El Jefe was believed to have been killed or migrated south to find a mate, but his spirit lived on through conservation efforts to protect the habitat for threatened and endangered species in the borderlands. Finally, during the summer of 2022, a camera trap in Sonora captured an image of legendary El Jefe, alive, healthy, and one of the oldest living jaguars. This image confirmed that El Jefe had indeed migrated south of the border, providing hope and inspiration to all fighting to protect viable habitats and migration corridors for jaguars and many other species in the U.S. and Mexico.


Native Grasslands: A Forgotten Ecosystem

Native grasslands are historically one of the largest biomes in North America, but due to crop production, urbanization, and livestock grazing, they have become one of the world’s most endangered ecosystems. Evidence suggests that bison, North America’s principal large grazing mammal, were uncommon in southeast Arizona or perhaps missing altogether after the end of the last ice age. Because the Southwest and Intermountain West grasslands survived and evolved without the presence of native hoofed grazers for 10,000 years or more, they were unprepared for and intolerant to the introduction of domestic grazers that began with the Spanish in the 16th century. They also are less understood because so many of them were altered almost out of existence by Euro-American colonization. For example, very arid grasslands in the Southwest were converted to desert scrublands by grazing. Today, livestock exclusion on those lands has little effect because the soil changes from historic overgrazing have rendered them incapable of supporting grasses.

Madera Canyon

Just slightly off route is Madera Canyon, one of the most famous birding areas in the United States. It is a north-facing valley in the Santa Rita Mountains with riparian woodland along an intermittent stream, bordered by mesquite, juniper-oak woodlands, and pine forests. Madera Canyon is home to over 250 species of birds, including 15 hummingbird species. Visitors from all over the world search for avian specialties such as the Elegant Trogon, Elf Owl, Sulphur-bellied Flycatcher, Red-faced Warbler, and Painted Redstart. A comprehensive bird list published by FoMC is available at the Proctor Visitor Info Station and at trailheads. (website)

Santa Rita Mountains

Serving as the focal point of the East Loop, the Santa Rita Mountains are the fourth highest of the Sky Island mountain ranges in southeastern Arizona and rise nearly 6,000 feet above the desert floor. They are incredibly rugged, with steep slopes, sharp peaks, and narrow ridges. Much of the vegetation is pine forest mixed into the oak-pine forest at lower elevations. Several of the deeper canyons have perennial streams and well-developed riparian communities.

Riders of the East Loop will experience grasslands on the south and east side of the Santa Rita Mountains, pine and oak-pine forests as they climb in elevation and ride through the Santa Rita’s foothills, and low-desert environment on the west side of the range, once they cross Box Canyon Pass on the north side of the course.

The Santa Rita Mountains are best known for their birding opportunities, particularly in Madera Canyon, dark night skies for stargazing, and being the habitat of the infamous Jaguar “El Jefe,” who was documented living in the Santa Rita Mountains from 2010-2015, until he migrated south to Sonora. 

San Rafael Valley

Starting in the counterclockwise direction, expansive views of the San Rafael State Natural Area welcome riders at the top of the first climb from Patagonia. The San Rafael State Natural Area is unique, with rolling hills, native grasses, and oak and cottonwood trees. This beautiful valley serves as the headwaters of the Santa Cruz River, which flows into Mexico, then turns north back into the United States and eventually joins the Gila River. While this valley is mainly private land and used for cattle grazing, much of the valley is protected by conservation easements to ensure that the sustainable grazing practices that have preserved this valley continues.

The riparian areas and native grass prairie in the San Rafael State Natural Area are home to many species of plants and animals, including; the endangered plant, Huachuca Water Umbel, the state-protected Sonoran Tiger Salamander, as well as mule deer, javelina, antelope, bobcats, cougar, coyote, and many birds unique to the prairie (website). As some of the last remaining un-fragmented prairie grassland habitat left in the American Southwest, this area is vital for grassland bird species. It is best known for wintering raptors, sparrows, pipits, and longspurs. 

The most relevant current conservation threat to the San Rafael Valley is mining. As the Santa Cruz River headwaters, this area is particularly vulnerable to the water depletion and fouling associated with mining. In addition, the Patagonia, Arizona, area is presently the location of multiple major mining exploration projects.

Rosemont Mine

While the Santa Rita Mountains provide essential habitat for threatened and endangered species, they, too are under threat by the proposed Rosemont Mine. This one-mile-wide, half-mile-deep open pit copper mine would destroy habitat, contaminate and drain the limited groundwater, and pollute the night skies with light.

Additional Resources on the Region

Sky Islands Region 

Things to do and see

You can find detailed information about places of interest and other such details on each individual route guide. Here’s a few of the places, sights, and points of interests that are along the routes. Each is referenced with the loop(s) with which they are associated.

Town of Patagonia (east, west, and full loops)

The charming town of Patagonia serves as the start and end point of all the Sky Islands Odyssey routes. Once a supply town for nearby mines and cattle ranches, today, Patagonia is home to multi generation ranching families, artists, conservationists, retirees, and a flurry of newcomers who are moving to the region specifically for its excellent access to trails and gravel roads. Among many of its varying hats, Patagonia serves as a trail community for Arizona Trail and the launching point for the growing popularity of gravel cycling in the San Rafael Valley. Home to local art galleries, a natural food co-op, a café, a hummingbird sanctuary, a new gathering place for cyclists, and a few places to stay, Patagonia remains a quiet desert hamlet with an eclectic vibe.

Town of Sonoita (east and full loops)

Sonoita serves as a little respite for resupply. Grab some food from the Sonoita Mercantile or Mini Mart, a meal at the Steak House Restaurant Saloon, a place to sleep at the Sonoita Inn, camp at the fairgrounds, or some ice cream at the Corner Scoop. Sonoita is literally and figuratively at a crossroads; as the only place to fill up with gasoline for miles around, it is a gathering place for ranchers, semi-truck drivers, recreationists, hunters, wine tasters, border patrol agents, and residents. In essence, enjoy the people-watching!

Sonoita Wine Country

There are approximately twenty wineries, meaderies, and cideries in the Sonoita Elgin area. With climate and soil conditions comparable to wine regions in California and Argentina, Arizona’s southern high deserts made the state a major player in international wine circles. Sonoita is one of the most prolific Arizona wine regions, with vast valley farmlands producing nearly three quarters of the state’s grapes to produce award-winning Sauvignon Blanc, Cabernet Sauvignon, Malbec and Merlot varietals.Sonoita was the first location in Arizona to be designated as an American Viticultural Area.

The Sonoita valley receives no outside water, relying entirely on rainfall; precipitation averages 17 inches per year. Climate change, urbanization, a dwindling water table in the Sonoita Valley, and the reality that each grape plant requires 960 gallons of water per season, will likely impact the sustainability of the Sonoita Wine Country in years to come. Read more here.

Kentucky Camp (east and full loops)

Kentucky Camp was built in 1904 as the headquarters of the Santa Rita Water and Mining Company, whose investors hoped to collect water from the Santa Rita Mountains for hydraulic gold mining. The venture was abandoned following the mysterious death of the chief engineer the following year. The property became a working cattle ranch for the next 50 years before being sold to a mining conglomerate. The Coronado National Forest acquired the site in 1989; since then, the forest and volunteers have been working together to preserve the site. Kentucky Camp (and associated features related to the development of the water system and mining in the area) is listed on the National Register of Historic Places.A unique feature of this site is its collection of five-century-old adobe buildings. The ten-room headquarters building is one of its era’s largest surviving adobe buildings. A three-room adobe building is available for overnight rental. Go to the Forest Service “Cabins and Camping” web page for additional details on renting this building. (website)

Juan Bautista De Anza Trail (east and full loops)

In 1775-76 Juan Bautista de Anza, an expeditionary leader, military officer, and politician primarily in California and New Mexico under the Spanish Empire, led some 240 men, women, and children on an epic journey to colonize the first non-Native settlement at San Francisco Bay. Today, the 1,200-mile Juan Bautista de Anza National Historic Trail connects history, culture, and outdoor recreation from Nogales, Arizona, to the San Francisco Bay Area. (website)

Ruta Del Jefe Event

Used as a platform to raise awareness about environmental and political threats affecting the US/Mexico borderlands of Southern Arizona, Ruta del Jefe, a 125-mile, self-supported adventure race following dirt roads around the Santa Rita Mountains and the lair of El Jefe, one of the few remaining North American Jaguars to live in the US. Find a few stories and past coverage linked here:

Route Development

The goal for the Sky Islands Odyssey Route(s) is to make an accessible multi-day journey along dirt roads, highlighting this region’s biodiversity and history while also raising awareness of the human and wildlife consequences of U.S. immigration policies. These routes were initially developed and scouted in 2017-2018 by Sarah Swallow and friends over seven separate reconnaissance missions to route the complex network of mismapped dirt roads and tracks in this region. To do this day, Sarah Swallow maintains and updates these routes multiple times a year.

Many of the resources and information included in this revised guide were collected and researched by Sarah during a two-year winter residency at the Appleton-Whittell Research Ranch, in Elgin, from 2020 to 2022. Sarah hosted Ruta del Jefe on the Sky Islands East Loop in 2019, 2020, and 2022. Sarah also hosts the Sky Islands Adventure Ride series every winter, a series of group adventure rides highlighting some of the Sky Islands Odyssey segments and the Tucson cycling community. In 2023 the Sky Islands East and Full Loops underwent a significant reroute after management changed at Appleton-Whittell Research which led to them no longer accepting cycling permits. Along with the update, Sarah released gravel-bike friendlier versions of the East Loop and Full Loop to make the routes more accessible to all. Sarah keeps a collection of the most up-to-date route versions and variations, in her Sky Islands Odyssey Ride with GPS Collection.

Campfire Cycling in Tucson, Arizona, has served bikepackers of the Sky Islands Odyssey Loops since their inception by providing up-to-date conditions and weather along with any last-minute gear and maintenance needs. In addition, Campfire Cycling hosts at least one guided group tour annually on the Sky Islands Odyssey loops.

If you ride and enjoy your time on one of the Sky Islands Odyssey routes, please donate a few bucks to the Sky Islands Odyssey Route Project to support, maintain, develop, and promote these routes for years to come. Similarly, the Sky Islands Odssey Route Project is seeking community feedback to grow and develop in the future. If you ride any of the routes, please provide your feedback by filling out this form.