The Great Mountain Lock: A First Frontier Story
The Great Mountain Lock: A First Frontier Story of the Long Road West
There are places on a map that look unremarkable until you understand what you are looking at. A creek comes down from the mountains, another joins it, and together they pass beneath a highway bridge before disappearing into the modern landscape. There may be a gas station, a convenience store, a warehouse, a railroad track or a strip of woods nearby. Nothing about the scene necessarily announces that it is important. Yet some landscapes have a peculiar ability to preserve their usefulness across centuries. The names change, the technology changes, the people change and the political boundaries change, but the geography remains stubbornly the same. A mountain gap that once carried Indigenous travelers can later carry a wagon road; the wagon road becomes a turnpike; the turnpike gives way to a railroad; the railroad is joined by a highway. What appears to us as a modern transportation corridor may actually be the latest expression of a route that people have been using for hundreds, perhaps thousands, of years.
There is such a place in central Pennsylvania, tucked into the landscape between Hollidaysburg and the Allegheny Front. At the confluence of the Beaverdam Branch of the Juniata and Blair Run, just upstream from what is now Old Route 220 or locally Plank Road, the terrain opens toward several natural passages through the mountains. Follow the Beaverdam Branch northwest and the landscape leads toward Kittanning Gap and eventually toward the Allegheny River at Kittanning and the Ohio country. If you choose west through Blair Run Gap and the route rises toward Cresson and the Conemaugh Valley. Between them lies Sugar Run Gap, another natural passage through the Allegheny barrier.
From the Kittanning Gap south to Blair Run Gap is only 5.9 miles but these three passes are one of the most important historically dense corridors in America. While freight planners identify four primary highway/rail bottlenecks over the Mississippi River, there are only three natural corridors across the Appalachians: The Mohawk Gap / Hudson Valley in New York; The Cumberland Gap on the KY/TN/VA border; and here. This is where a series of river-carved notches through the Ridge-and-Valley Appalachians, providing natural ramps for land passage toward Pittsburgh and the Ohio Valley.
The Alleghenies were never an impenetrable wall. They were something more complicated: a natural lock, forcing generations of travelers into a handful of passages through the mountains.
The Alleghenies were never an impenetrable wall. They were something more complicated: a natural lock, forcing generations of travelers into a handful of passages through the mountains.
I call it The Great Mountain Lock of the First Frontier.
A lock, in the sense I use it here, has two meanings. It can be a device that secures a door or passage, opened only with the right key. It can also be the chamber of a canal, bounded by gates, that raises or lowers a boat between different elevations and then releases it to continue its journey. The Alleghenies functioned as both. The mountains created a formidable barrier to east-west movement, but they also concentrated that movement into a handful of passages where the barrier could be overcome. For centuries, travelers arrived at those passages with different needs and increasingly sophisticated tools: first the human foot, then the packhorse and wagon, the turnpike, the canal and portage railroad, the locomotive, and finally the automobile. Each was another attempt to negotiate the same geographic obstacle and continue westward. The mountains remained in place. The key kept changing.
The Path
Long before Pennsylvania had roads, bridges or surveyed property lines, people had already learned how to move through this landscape. The Kittanning Path was one of the principal Indigenous routes across the Allegheny Mountains, connecting the Juniata River country of central Pennsylvania with the Lenape village of Kittanning on the Allegheny River. It was not necessarily a single, precisely defined trail in the modern sense, but rather a network of routes and alternatives that allowed travelers to navigate one of the great geographic barriers of the eastern United States. The Alleghenies were not impossible to cross, but they were difficult enough that the locations of practical gaps, valleys and watersheds mattered enormously. Travelers learned which passages offered the gentlest grades, which valleys provided water and which routes could be used depending upon the season, weather or the nature of the journey. The mountain itself dictated the broad outline of the path.
Travelers learned which passages offered the gentlest grades, which valleys provided water and which routes could be used depending upon the season, weather or the nature of the journey. The mountain itself dictated the broad outline of the path.
The Kittanning Path was used by generations of Indigenous peoples, including Iroquoian-speaking peoples and Algonquian-speaking Lenape, Miami and Shawnee. It connected the river valleys east of the Alleghenies with the highlands and western drainage of the Ohio country, passing through what are now familiar Pennsylvania communities and landscapes. European traders and settlers eventually adopted these routes for the same reason Indigenous travelers had: the paths represented the practical ways through a difficult mountain system. The landscape had already solved the fundamental transportation problem. Europeans did not need to invent the route so much as recognize it, widen it and eventually formalize it.
From the Juniata River near Frankstown, the path crossed the Allegheny Ridge through Kittanning Gap, approximately where the Pennsylvania Railroad would later construct Horseshoe Curve. From there it continued westward through the mountains, eventually reaching Kittanning on the Allegheny River. The route that we now associate with transportation infrastructure therefore predates the infrastructure by centuries. The railroad did not discover Horseshoe Curve. The highway did not discover the mountain gap. The turnpike did not discover the valley. Each simply inherited a geographic solution that had already been tested by generations of travelers.
That distinction matters because it changes how we understand the landscape. The history of transportation in this part of Pennsylvania is not really a succession of completely new routes replacing old ones. It is more often a succession of technologies occupying the same geographic corridor. The path becomes a road because the road follows the path. The turnpike follows the road because the road has already identified the easiest crossing. The railroad follows the valley because the valley provides the grades a locomotive can manage. The highway follows the railroad because the mountain still presents the same obstacle. The technology is modernized; the geography is not.
A Path Becomes a Warpath
By the eighteenth century, the Kittanning Path had become much more than a means of travel. The Allegheny Mountains formed a frontier between competing peoples and colonial interests, and the routes through them became strategic corridors. During the French and Indian War, Indigenous war parties used the established paths to move rapidly between settlements, while British colonial forces followed those same routes in pursuit of them. A trail that had carried traders and travelers for generations became a route for military campaigns, raids and retaliation.
In the 1750s, Lenape war parties used the Kittanning Path to move eastward toward British settlements along the Juniata. In 1755, Chief Shingas used the route during attacks on settlements in central Pennsylvania. The following year, a Lenape raid resulted in the destruction of Fort Granville near present-day Lewistown and the capture of prisoners. These were not random movements through the wilderness. The people conducting them were using a transportation network whose existence was already well established, taking advantage of the same geographic corridors that had enabled peaceful travel.
Then came the counterstroke. Following the destruction of Fort Granville, Colonel John Armstrong led a British colonial expedition westward along the same general route. He followed the path through the mountains, eventually reaching Kittanning in September 1756 and destroying the village. Armstrong became known among British colonists as the “Hero of Kittanning,” and the episode became one of the better-known military actions of the French and Indian War in Pennsylvania. Yet even this violent chapter was temporary. After the expedition the chiefs of 13 native tribes signed the Treaty of Easton, in which the natives agreed not to fight on the side of the French in the ongoing war, in return for the British returning land to them. Meanwhile, the path that had become a warpath would eventually become a road again, because the underlying need to cross the mountains never disappeared.
The Battle at Sugar Run
The history of these corridors is not confined to famous campaigns. Sometimes it survives in places that today appear almost completely ordinary. On the morning of June 3, 1781, during the American Revolution, a detachment of Bedford County militia and local volunteers left Fort Fetter (between Duncansville and Hollidaysburg) in pursuit of a reported Indigenous war party that had entered the Tuckahoe Valley (Altoona), killed a settler and taken his wife captive. The men moved north along established routes toward the mountain country, intending to find the raiders and recover the captive.
Instead, they walked into a trap.
The men moved north along established routes toward the mountain country, intending to find the raiders and recover the captive. Instead, they walked into a trap.
Near the Beaverdam Branch, a short distance downstream from Sugar Run, the Bedford County troops were ambushed. The earlier attack had apparently been designed to lure the militia out of the protection of their fortifications. British soldiers and Seneca warriors had moved into the area and waited along the route. When the Bedford County Rangers approached, the attackers emerged from the morning fog and opened fire with muskets and arrows. The engagement was brief but deadly. Approximately fifteen of the Bedford County men were killed, five wounded and seven captured, including Captain John Boyd. The attacking force also suffered casualties.
Today, the location is marked by monuments that are easy to overlook amid the modern landscape. The original marker stands along Route 764, while a newer monument was dedicated nearby in 2021. Traffic passes through the area every day. People stop at nearby businesses, drive to work, buy gasoline and go about the ordinary business of modern life. Yet the landscape has not forgotten what happened there. The same waterways and mountain passages that guided travelers centuries ago also guided soldiers into one of the region's lesser-known Revolutionary War engagements. History did not happen somewhere else. It happened along the same routes we still use.
The Road
As the frontier moved westward after the American Revolution, the old Indigenous paths increasingly became formal roads. The need was no longer simply to move people across the mountains but to move families, livestock, agricultural products and commercial goods. The emerging United States was expanding beyond the Appalachian barrier, and Pennsylvania faced the enormous challenge of connecting its eastern population centers with the growing settlements and markets of the West.
The Huntingdon, Cambria and Indiana Turnpike was one answer. Authorized in 1810 and completed around 1819, the approximately 77-mile toll road connected Huntingdon with Blairsville and became an important commercial route across the Alleghenies. At first it was little more than a rough, unpaved track capable of handling pack animals and heavy Conestoga wagons. But compared with the uncontrolled wilderness routes that preceded it, a maintained turnpike represented a major investment in infrastructure. Toll gates provided revenue for maintenance, and travelers paid for the privilege of having a defined route through some of the most difficult terrain in Pennsylvania.
The turnpike also demonstrates another recurring feature of this landscape: infrastructure rarely erases what came before. It builds upon it. The engineers who established the road up Blair Run Gap from Hollidaysburg to Cresson were working within the same fundamental geography that had guided Indigenous travelers. The route climbed through the mountain gaps because those gaps offered practical grades. It followed valleys because valleys provided natural corridors. It crossed streams at places where crossings were possible. The road was new, but the logic behind it was ancient.
Eventually, the turnpike encountered an even more ambitious transportation project. Pennsylvania wanted to connect Philadelphia and Pittsburgh through a combination of canals and railroads, creating its own answer to the economic advantages New York had gained from the Erie Canal. Once again, the problem was the Allegheny Mountains.
The Canal Comes to the Mountains
The completion of the Erie Canal in 1825 transformed transportation between the Atlantic seaboard and the Great Lakes. New York had found a comparatively gentle route through its geography, and Pennsylvania faced the uncomfortable realization that its own western trade might be captured by its northern neighbor. The Commonwealth responded with the Main Line of Public Works, an enormous transportation project intended to connect Philadelphia and Pittsburgh.
The geographic obstacle was obvious. The Allegheny Mountains stood between the two cities.
The Commonwealth responded with the Main Line of Public Works, an enormous transportation project intended to connect Philadelphia and Pittsburgh. The geographic obstacle was obvious. The Allegheny Mountains stood between the two cities.
The proposed solutions were extraordinary. At one point, engineers considered constructing a canal tunnel more than four miles long between Duncansville and Lilly. This was the 1830s, decades before dynamite, when engineers and laborers depended upon hand tools and black powder. The scale of the proposal reveals just how important the connection to the West had become. Pennsylvania was willing to contemplate an enormous engineering undertaking because the alternative was economic isolation.
The final solution was the Allegheny Portage Railroad. Construction began in 1831, and the approximately 36-mile section between Hollidaysburg and Johnstown opened in 1834. It was not a conventional railroad in the modern sense. Instead, canal boats were transferred onto railroad cars and hauled over the mountain using a combination of level stretches and inclined planes. Stationary steam engines pulled the cars up and lowered them down the steep sections, allowing canal traffic to cross the Allegheny Ridge.
The system was a technological marvel for its time. Five inclined planes climbed one side of the mountain and five descended the other, connected by level stretches of railroad. The entire Main Line system from Philadelphia to Pittsburgh stretched approximately 400 miles and could reduce a journey that had once taken weeks by wagon to roughly four days. For a young country still pushing its population and commerce beyond the Appalachians, the importance was enormous. The Allegheny Portage Railroad was not simply a local transportation project. It was part of the infrastructure that helped connect the eastern seaboard with the interior of the continent.
But transportation technology was accelerating. The Portage Railroad solved one problem only to be overtaken by another.
The railroad was coming.
The Rails
In 1846, competing proposals reached the Pennsylvania legislature for railroads that would connect the eastern portion of the state with Pittsburgh. The Pennsylvania Railroad eventually secured the charter and began developing a route across the Commonwealth. Its chief engineer, John Edgar Thomson, understood the fundamental problem immediately: the company did not need to conquer the Alleghenies. It needed to find the most practical way through them.
The railroad followed the Juniata River westward until it reached the mountains near what would become Altoona. There, the valley divided into two ravines. A railroad could not simply climb directly up the mountain; the grade would be too steep for the locomotives of the period. Thomson's solution was to use the terrain itself to create a longer, gentler ascent. The result was Horseshoe Curve, an enormous arc that wrapped around the mountain and allowed the railroad to gain elevation while keeping the grade within manageable limits.
Construction began in 1850 using methods that now seem almost impossibly primitive. Men with picks and shovels, assisted by horses and drags, moved enormous quantities of earth. One ravine was filled, another was cut through, and the railroad was gradually built into the mountainside. The 31-mile section between Altoona and Johnstown opened in February 1854. The Pennsylvania Railroad had established a continuous rail connection across the Alleghenies, and the old canal-portage system quickly became obsolete.
Possibly the first known photograph of the iconic Horseshoe Curve, taken around 1854
The irony is difficult to miss. The Portage Railroad had been considered one of the great engineering achievements of its age. It had taken years to construct and represented a massive investment by the Commonwealth. Yet within two decades, a new technology had made much of it unnecessary. Transportation history is often told as a story of progress, but standing in this landscape reveals something more complicated. Each new system leaves behind the physical evidence of the one before it. Abandoned grades, old bridges, tunnels, roads and alignments become layers in the landscape, each representing the moment when a particular generation believed it had solved the transportation problem once and for all.
Transportation history is often told as a story of progress, but standing in this landscape reveals something more complicated. Each new system leaves behind the physical evidence of the one before it.
After Horseshoe Curve, the railroad faced its final challenge at Sugar Run Gap. The solution was to go through the mountain itself. The Gallitzin Tunnels became another essential component of the Pennsylvania Railroad's main line, with the original Allegheny Tunnel completed in 1854 and additional bores constructed as traffic increased. By the twentieth century, the corridor had become one of the most important rail routes in the country, carrying passengers, coal, manufactured goods and military equipment between the East and the industrial interior.
Even during World War II, the strategic importance of the route was recognized by America's enemies. The German Abwehr's 1942 Operation Pastorius targeted major American industrial and transportation assets, including Horseshoe Curve. The would-be saboteurs were captured before carrying out their plans, but the episode illustrates how important this seemingly ordinary mountain corridor had become. A path once used by Indigenous travelers and war parties had become critical infrastructure for an industrial nation at war.
Even today, this corridor serves as a site of global importance.
The Road Returns
The turnpike eventually surrendered its dominance to the railroad. Toll collection ended around 1870 as rail transportation became more efficient and economical for passengers and freight. But the old right-of-way did not disappear. Like the Indigenous path before it, the road had established itself in the landscape, and the geography that made it useful remained.
Then the automobile arrived.
The old corridor was paved and incorporated into the emerging highway system. U.S. Route 22 became part of the original United States highway system established in 1926, and the William Penn Highway followed much of the same general route through the mountains. In places, the modern highway sits directly over or beside the older transportation corridors. In others, the historic road survives as a local street or secondary alignment. What appears to be a modern highway is therefore sometimes the newest layer of a route that has existed in one form or another for centuries.
By the middle of the twentieth century, Route 22 had become a major automobile corridor. The highway was widened and redesigned as traffic increased, including the 1952 configuration near Cresson that featured a shared center passing lane. For people who grew up in the region, this period produced its own local folklore. My grandfather and father remembered teenagers coming from across the two-county area to test the limits of their hot rods on the mountain, only to discover that the local police were equally familiar with the capabilities of their own automobiles. One officer was remembered for pursuing speeders in a Studebaker Golden Hawk powered by a Packard V8, a machine whose performance made it unusually well suited to the mountain roads it patrolled.
It is an amusing footnote compared with the battles, canals and railroads that came before, but it belongs to the same story. Every generation finds its own way to test itself against the mountain. The technology changes, but the relationship between people and the landscape remains remarkably consistent.
Beginning in the late 1980s, another major transformation arrived. Route 22 was expanded into a modern four-lane divided highway between Duncansville and Ebensburg, with a massive multi-year project eventually connecting Pittsburgh and Altoona through a continuous four-lane corridor. Once again, engineers confronted the same fundamental question that had faced Indigenous travelers, turnpike builders and railroad engineers centuries earlier: which passage through the mountains makes the most sense?
This time, the answer was the middle route.
Sugar Run Gap.
The Mountainhouse
For me, this history is not entirely abstract. I grew up a stone's throw from the original alignment of Route 22 in Cresson, in a neighborhood known as the Mountainhouse Grounds. The name itself preserves another chapter of the corridor's history. The Mountainhouse Hotel was built by the Pennsylvania Railroad in 1881 as a resort intended to attract visitors from Pittsburgh and Johnstown seeking the clean mountain air and therapeutic mineral springs. During its heyday, the surrounding community attracted some of the country's most prominent industrialists, including Andrew Carnegie, Charles M. Schwab and Henry Clay Frick.
Several of the original cottages remain. Carnegie eventually donated hundreds of acres of his property, and the surviving houses provide a physical connection to an era when the railroad had transformed the Alleghenies from an obstacle into a destination. Wealthy industrialists who had made fortunes from the country's rapidly expanding industrial economy could now escape the cities by taking the same transportation system that helped build those fortunes.
I grew up cattycorner from one of those cottages. As a child, it was simply part of the neighborhood. I did not understand that the road outside my house represented another chapter in a transportation story that stretched back centuries, or that the mountains surrounding Cresson had already been crossed by Indigenous travelers, soldiers, wagon drivers, canal boats and locomotives long before automobiles arrived. Geography has a way of making history ordinary when you live inside it. Later, in the mid to late 1980’s, our family moved to the top of the summit at Tunnelhill. The namesake of the community offers a clue as its place in this story. Then in the mid-2000 teens and early 20s, my apartment in Hollidaysburg (once housed the town's telegraph office) was above the old William Penn Highway. Now it is known as Allegheny Street.
The Gates
Stand today near the confluence of the Beaverdam Branch and Blair Run and there is little about the scene that announces its importance. A Baker Brothers Memorial Bridge carries modern traffic. Nearby businesses like a convenience store, a hotel, a brewery and a restaurant occupies the surrounding landscape. The waterways continue toward the Juniata River. A small ribbon of woodland survives between roads and development. It is entirely possible to pass through without giving the place a second thought.
Yet from this point, the geography begins to reveal itself. Follow Beaverdam Branch northwest and the landscape leads toward Kittanning Gap. Travel west through Blair Run Gap and the route rises toward Cresson and the Johnstown country. Take the central passage through Sugar Run Gap and you enter another of the natural corridors that have repeatedly carried transportation across the Allegheny Front. These are not arbitrary lines drawn by surveyors. They are routes dictated by the underlying geology, drainage and topography of the mountain range.
The mountain presents a problem, and generation after generation arrives at essentially the same answer.
That is what makes this particular corridor so historically significant. It is not simply that an Indigenous trail once existed here, or that a turnpike later crossed the mountains, or that the Pennsylvania Railroad built Horseshoe Curve and the Gallitzin Tunnels, or that modern Route 22 still carries traffic through the region. It is that all of these systems are responding to the same geographic reality. The mountain presents a problem, and generation after generation arrives at essentially the same answer.
The Kittanning Path became a route for war parties and traders. The warpath became a road used by settlers moving west. The road became a turnpike carrying wagons and commercial freight. The Commonwealth built canals and the Allegheny Portage Railroad to connect the eastern and western markets. The Pennsylvania Railroad replaced the portage system with a continuous rail connection. The automobile transformed the old roads into highways. Modern Route 22 widened and straightened portions of the corridor, but it still climbs through the same mountain passages.
The infrastructure changed because technology changed. The routes changed remarkably little because the mountain did not.
The infrastructure changed because technology changed.
The routes changed remarkably little because the mountain did not.
There is something humbling about that continuity. We tend to think of transportation as an expression of human ingenuity, and it certainly is. The bridges, tunnels, locomotives, inclined planes, highways and machines that occupy this landscape represent extraordinary engineering achievements. But there is another story beneath that one. The engineers were constrained by a landscape that had already been here for millions of years. Their greatest achievement was not necessarily inventing a route, but recognizing the route the land would permit.
This is why I think of this landscape as The Great Mountain Lock at the First Frontier.
The phrase “frontier” usually evokes a boundary, a line separating the known from the unknown. But in Pennsylvania, the first frontier was not an empty wilderness waiting to be discovered. It was a landscape already traveled, named and understood by Indigenous peoples who had developed sophisticated networks of movement across it. Europeans entered that landscape and adopted many of those existing corridors. The frontier shifted westward, but the routes through the mountains remained.
Today, many of the physical remnants of that story are scattered across the landscape. Some remain active: Route 22 carries modern traffic, while freight trains continue to move through the railroad corridor. Some have become historic sites, including the Allegheny Portage Railroad and Horseshoe Curve. Some have become trails, allowing modern travelers to follow abandoned transportation corridors at a pace more reminiscent of the people who first traveled them. Others have simply disappeared beneath pavement, development and time.
But they are still connected.
The path, the road, the canal, the railroad and the highway are not separate histories. They are chapters of the same story.
The path, the road, the canal, the railroad and the highway are not separate histories. They are chapters of the same story.
And perhaps that is the most important thing this landscape has to teach us. We like to imagine that each generation builds its own world, replacing what came before with something newer, faster and more efficient. But in places like this, the past is rarely completely replaced. It is layered. The modern highway rests beside the old road. The railroad occupies the mountain gap first identified by travelers centuries ago. A trail may follow a former railbed that once carried freight across the same valley where an Indigenous path once carried people on foot.
The names change. The machines change. The purpose of travel changes. Even the people moving through the landscape change.
But the locks remain.
For centuries, people have approached these mountains and looked for a way through. They found the same valleys, the same gaps and the same corridors that we use today. They built upon them, widened them, paved them, tunneled through them and eventually built machines capable of crossing them at speeds their predecessors could scarcely imagine.
Yet none of those achievements changed the fundamental geography.
The Alleghenies still stand.
The rivers still find the lowest ground.
The gaps still provide the easiest passage.
Generation after generation arrived at the same problem: how do you get through the mountains? Each brought a new answer. The paths became roads, the roads became railroads, the railroads gave way to highways.
The frontier moved west.
The technology moved forward.
But the lock itself never moved.
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