Top 10 Largest Glaciers in the United States

#1: Bering Glacier (Alaska — Length: 118 mi; Area: 1,900 sq mi)

Bering Glacier reigns as North America’s longest, snaking 118 miles through Alaska’s Chugach Mountains before spilling into Vitus Lake. Its 1,900 square‐mile drainage basin once nourished mighty salmon runs—Indigenous Alutiiq communities still recount legends of ice‐fed streams teeming with fish so abundant they seemed bottomless. Sighted by Vitus Bering in 1741, the glacier remained largely unmapped until 20th‐century aerial surveys. In 2002, Bering made headlines when an unprecedented surge dammed Vitus Lake, raising its level by 30 feet before a spectacular calving breach sent icebergs cascading downstream, reshaping the shoreline and thrilling researchers who had deployed GPS buoys to monitor the event. Beneath its surface, ground‐penetrating radar has unveiled relic forests—ancient spruce and hemlock trunks buried by ice 10,000 years ago—offering time capsules of Pleistocene ecosystems. Recent studies reveal that Bering’s velocity fluctuates dramatically: warm summers and heavy snowfall fuel rapid advances, while cold winters and subglacial friction slow its pace. Today, satellite imagery tracks its retreating snout and thinning upper reaches, markers of Alaska’s warming trends. Yet the glacier’s complex behavior—alternating between surge and stagnation—underscores how local topography and climate interplay to shape glacier dynamics. For adventurers, guided kayak tours through Vitus Lake’s iceberg-strewn waters offer up‐close views of towering ice cliffs, while intrepid mountaineers explore hidden ice caves beneath its overhanging seracs. Bering Glacier stands as an ode to nature’s power, its living ice archive chronicling centuries of change.

#2: Malaspina Glacier (Alaska — Length: 65 mi; Area: 1,500 sq mi)

Spilling from the St. Elias Mountains into the Gulf of Alaska, Malaspina Glacier is the world’s largest piedmont glacier—its ice fan stretching across 65 miles and covering roughly 1,500 square miles. First charted by Spanish explorers under Alejandro Malaspina in 1792, this frozen delta defies simple classification, its multiple lobes carving distinctive braided channels through coastal forests. In the 1930s, aerial photographs revealed dramatic meltwater floods, prompting engineers to study its impact on nearby copper mines. Beneath the ice, geothermal springs lurk, their warm effluent fostering microbial mats unseen elsewhere in Alaska. In 2015, marine biologists studying its terminus discovered schools of herring seeking refuge beneath ice overhangs, an unlikely cold-water sanctuary. Recent GPS surveys show that warmer ocean currents undercut the glacier’s edge, triggering calving events that punctuate the tranquil scene with thunderous roars. A 1980s surge advanced one lobe nearly a mile, drawing scientific intrigue into piedmont surge mechanisms. Cultural lore among the Yakutat Tlingit speaks of “spirit lights”—ethereal glows seen deep within Malaspina’s crevasses on stormy nights—a phenomenon now attributed to biophysical fluorescence from subterranean algae trapped in refrozen meltwater. As global temperatures climb, Malaspina’s immense mass serves as both a freshwater reservoir and a barometer of coastal climate shifts. Day‐trip cruises from Yakutat offer tourists surreal vistas of towering seracs, while glaciologists deploy drones to map its hidden topography, piecing together how ice, ocean, and geothermal heat collide in one of Earth’s most immense and dynamic glaciers.

#3: Baird Glacier (Alaska — Length: 55 mi; Area: 275 sq mi)

Tucked within Glacier Bay National Park, Baird Glacier meanders some 55 miles from its origins near Mount Hay to its snout at Adams Inlet. Though dwarfed by neighboring icefields, its 275 square‐mile expanse holds a pivotal place in the history of American glaciology: in 1879, naturalist John Muir led an expedition through Glacier Bay, mapping Baird and neighboring ice streams, then part of a much larger ice complex. Muir’s journals describe the astonishing “whiteness of a thousand miles of ice,” and his writings helped catalyze the creation of Glacier Bay National Monument in 1925. Baird’s temperamental behavior—advancing during cold, wet periods and retreating in warm, dry decades—mirrors regional climate oscillations. In the 1990s, rapid warming caused its terminus to pull back nearly three miles in just twenty years, revealing forested ridges dotted with tree stumps dated to the Little Ice Age maximum. Ice-rafted debris studies trace sediment layers deposited in tidewater, painting a picture of episodic surges that once dammed bay waters and formed ephemeral proglacial lakes. Modern kayakers paddle amid sculpted ice floes calved from jagged cliffs up to 100 feet high, while researchers tag harbor seals that haul out on icebergs, revealing unexpected patterns of marine mammal use in glacial environments. Subsurface sonar mapping uncovered a deep inlet beneath the ice, likely carved by Baird during its 18th-century highstand. Today, its shrinking front offers a living classroom for students of glaciology, illustrating how swiftly ice responds to temperature shifts.

#4: Hubbard Glacier (Alaska — Length: 76 mi; Area: 1,000 sq mi)

Rivaling Bering in length at around 76 miles, Hubbard Glacier flows from the Yukon Territory into Alaska’s Disenchantment Bay. Named for Gardiner Hubbard, a founding president of the National Geographic Society, it’s famed for its periodic advances: in 1986 and again in 2002, Hubbard’s snout surged across the bay entrance, damming Russell Fjord and raising water levels by over 20 feet before breaching in spectacular calving floods. These events inspired emergency studies on flood risk and led park managers to install monitoring stations that warn local communities of sudden breaches. The glacier’s ice bears a distinctive cerulean hue—a result of dense compression expelling air bubbles—which makes its towering cliffs glow in sunlight. Scuba divers documenting underwater ice walls encountered cold‐water octopuses and brittle stars inhabiting niches under submerged shelves. In the early 20th century, gold‐rush prospectors floated rafts of ice to cool saloons in Yakutat, leveraging Hubbard’s abundant calving output. Today, cruise ships glide close enough for passengers to feel the glacier’s tremors as massive bergs detach. GPS studies link Hubbard’s surges to heavy snowfall in its accumulation zone, underscoring how winters laden with deep snowpacks prime the glacier for sudden advances. As sea ice thins in the Gulf of Alaska, Hubbard’s oscillations serve as a reminder that not all glaciers retreat monotonically—instead, some offer periodic bursts of growth that captivate both scientists and sightseers.

#5: Columbia Glacier (Alaska — Length: 51 mi; Area: 325 sq mi)

Columbia Glacier, coursing 51 miles from the Chugach Mountains into Prince William Sound, spans approximately 325 square miles. Once one of the world’s fastest‐retreating glaciers, Columbia astonished scientists in the 1980s and ’90s by accelerating from flows of 300 feet per year to over 10,000 feet per year at its terminus. This dramatic speed‐up—driven by thinning ice tongues and increased submarine melting—made Columbia a poster child for tidewater glacier instability. Observers noted daily calving events that reshaped fjord bathymetry, while acoustic sensors recorded calving booms felt miles away. The glacier’s retreat exposed plateaus where archaeological teams unearthed pre‐contact Indigenous artifacts preserved beneath ice for centuries, linking Pacific coastal cultures to ancient glacial extents. Ecologists have since documented the rapid colonization of newly exposed moraines by pioneering plant species, offering a real‐time view of ecological succession. Satellite‐guided drones now monitor serac collapses that once endangered research vessels. For adventurous kayakers, navigating the labyrinth of icebergs in Columbia’s calving zone provides a visceral sense of nature’s power, while scientists deploy autonomous underwater vehicles to gauge meltwater plumes that fuel plankton blooms vital to salmon fisheries. Columbia Glacier’s narrative of rapid transformation underscores the urgency of understanding tidewater glacier responses to climate warming.

#6: Taku Glacier (Alaska — Length: 58 mi; Area: 580 sq mi)

Nestled in the Tongass National Forest, Taku Glacier stretches roughly 58 miles from Interior icefields to Taku Inlet, covering about 580 square miles. Unlike many of its neighbors, Taku remained in a state of net advance well into the late 20th century—an anomaly attributed to heavy snowfall and a deep proglacial fjord that buttressed its snout, preventing calving. Early explorers in the 1880s chronicled its encroachment on the old Tlingit village of Klukwan, whose inhabitants relocated rather than live in the glacier’s shadow. Tree‐ring studies on stumps exposed by retreating ice reveal that Taku’s advance began around 1750 during the Little Ice Age peak. However, surveys after 1988 record a sudden shift: as ocean waters warmed, the stabilizing ice foot disintegrated, and by 2010 Taku began thinning and retreating. Marine biologists studying its inlet noted shifts in zooplankton communities linked to increased freshwater discharge. Meanwhile, kayakers tracing Taku’s shorelines pass by ice cliffs studded with stratified layers of dust from Asian desert storms, blown across the Pacific and embedded in the glacier. Geologists road‐mapped subglacial moraine ridges, uncovering evidence of prior surges centuries earlier. Taku Glacier’s turnaround—from advance to retreat—offers a poignant case study in how subtle environmental shifts can tip even the most stable glaciers into decline.

#7: Black Rapids Glacier (Alaska — Length: 27 mi; Area: 90 sq mi)

Though shorter at 27 miles, Black Rapids Glacier’s dramatic “gallop” into the Tanana River watershed in 1936–37 earned its place among glaciological legends. American geologist William O. Field coined the term “Black Rapids” after witnessing a rapid surge that sent its terminus plunging over 20 feet per day for weeks, an event that briefly made the glacier North America’s fastest moving. Local folklore attributes the surge to a curse laid by Athabascan elders angered by early prospectors’ intrusion; modern science links it to a build‐up of basal water pressure lubricating the ice bed. Despite retreating since the mid‐20th century, Black Rapids retains crevasse fields that challenge mountaineers seeking to recreate the surge expedition routes. Ice‐core samples reveal tephra from the 1912 Novarupta eruption, providing precise time markers within the glacier’s layers. A hidden gem lies in its lateral moraine trails, now verdant with wildflowers in summer, guiding hikers along what was once an active ice margin. Black Rapids stands as a fleeting monument to the unpredictable dynamism inherent in some glaciers.

#8: Mendenhall Glacier (Alaska — Length: 12 mi; Area: 13 sq mi)

Near Juneau, the easily accessible Mendenhall Glacier extends about 12 miles and covers roughly 13 square miles. Once reached by horseback in the late 19th century, today it draws hundreds of thousands of visitors annually to Mendenhall Lake’s scenic shores. Named after Edward Mendenhall, a U.S. Coast and Geodetic Survey superintendent, the glacier has retreated nearly two miles since 1750, exposing river channels now teaming with salmon during summer spawning runs. Interpretive trails wind through shockingly recent landscapes—forests no older than a century—while the visitor center showcases ice-berg calving time-lapses that captivate tourists. Unexpectedly, beneath the ice lies a network of meltwater caves that guide kayakers into chambers lit by sapphire-blue light; guided tours navigate narrow ice tunnels formed each winter. Climate scientists monitor seasonal mass balance through automated stakes, correlating melt rates to regional temperature anomalies. Mendenhall’s proximity to town offers a vivid lesson in glacial retreat: homeowners along Mendenhall Loop Road once reported icebergs stranding on their front lawns during periods of surge-driven advance. Today, outreach programs engage local schools in hands-on monitoring, nurturing the next generation of cryosphere stewards.

#9: South Sawyer Glacier (Alaska — Length: 14 mi; Area: 37 sq mi)

Flowing from the Juneau Icefield into Tracy Arm, South Sawyer Glacier spans around 14 miles and covers about 37 square miles. Less visited than nearby Mendenhall, its remote fjord setting yields dramatic tidal calving displays: icebergs the size of houses topple with thunderous crashes, sending waves that rock passing cruise vessels. In 2015, researchers deploying time‐lapse cameras captured a record-breaking four major calving events in a single hour, prompting studies into the glacier’s sensitivity to ocean temperature fluctuations. Marine ecologists document a phenomenon known as “ice‐scour,” where retreating ice gouges seabed communities, creating a mosaic of recolonization by barnacles, anemones, and soft corals. Kayak guides report sightings of transient orcas hunting salmon near the glacier face, capitalizing on fish stunned by sudden changes in water salinity. Subglacial sonar mapping reveals a deep underwater canyon beneath the glacier, carved by centuries of ice flow—an underwater wonder now being explored by remotely operated vehicles. South Sawyer’s raw grandeur and relative solitude make it a favorite among photographers seeking ice silhouettes against steep granite walls.

#10: Gannett Glacier (Wyoming — Length: 1 mi; Area: 1.8 sq mi)

Rounding out our list—though much smaller in scale—is Gannett Glacier in Wyoming’s Wind River Range. Stretching just over a mile and covering 1.8 square miles, it sits on the north slope of Gannett Peak, Wyoming’s highest summit. First documented by early surveyors in the 1870s, Gannett Glacier feeds streams that eventually join the Green River, a tributary of the Colorado River Basin. Though diminutive, its high‐altitude position—above 13,000 feet—makes it one of the most climate‐sensitive glaciers in the Lower 48. Studies reveal that Gannett has lost over half its volume since the 1920s, retreating uphill and thinning dramatically. Botanists exploring the forefield discovered alpine sedges colonizing newly exposed gravel, marking nature’s swift reclamation. Climbers ascending the glacier report crevasse‐hidden snow bridges that require cautious probing, while mountaineering guides share stories of heroic rescues during sudden storms. Ice cores from Gannett capture local dust events and summer melt layers, offering fine‐scale records of regional climate variability. As one of the few glaciers in the contiguous United States, Gannett serves as a sentinel for Lower 48 cryosphere health—its modest dimensions belie its outsized importance in understanding mid-latitude glacier responses to warming.

Conclusion

From Alaska’s sweeping giants—Bering, Malaspina, and Hubbard—to the more modest yet vital ice fields of Juneau and Wyoming, the United States’ largest glaciers chart a narrative of exploration, environmental change, and resilience. Each glacier, whether an icefield stretching hundreds of square miles or a high‐altitude pocket of ice in the Rockies, offers unique insights into climate history, ecological adaptation, and human interaction with frozen landscapes. As global temperatures climb and glaciers worldwide face accelerated retreat, these American ice giants remind us of the fragility and wonder of the cryosphere—and the urgent need to study, appreciate, and protect these majestic rivers of ice for generations to come.