Three Locks
Granville Township, Mifflin County, Pennsylvania
Marker Inscription
Preserved here are three locks of the Pennsylvania Canal, Juniata Division. Unique in that three locks and levels were adjacent. Stonework and the old bed of the canal can be seen.
Erected by Pennsylvania Historical and Museum Commission
The Story
Preserved here are three locks of the Juniata Division of the state-built Pennsylvania Canal, notable because three locks and their levels sat side by side—an unusual concentration on the line. Opened in the canal-building era of the 1830s, this waterway carried boats over the ridges between the Susquehanna and the west. The old stonework and the traced bed of the canal still mark the route.
Why it matters
The Three Locks are a tangible remnant of Pennsylvania's ambitious state canal system, an engineering answer to crossing the Appalachians before the railroads made it obsolete.
The story behind this marker
AI contextThe era
In the decades after the Revolution, the young United States faced a stubborn problem: the Appalachian ridges walled the settled seaboard off from the fast-growing country beyond. Roads over the mountains were slow and punishing, and moving heavy freight by wagon was ruinously expensive. When New York's Erie Canal opened a water route to the west in the 1820s, Pennsylvania felt the pressure keenly — Philadelphia's merchants feared losing western trade to their northern rival.
The state's answer was a bold, publicly funded system of canals and, later, inclined-plane railroads knitted together to cross the mountains. This spot lies on the Juniata Division, the branch that followed the Juniata River westward from the Susquehanna, threading a valley that had guided travelers toward the interior for generations.
The Early Republic was an age of civic ambition, when states borrowed heavily and bet their treasuries on grand public works. A canal was a machine made of water and stone: to lift or lower boats as the land rose, engineers built locks — walled chambers whose water level could be raised and dropped. The stonework preserved here is a surviving fragment of that enormous, hand-built undertaking.
People & events
The story here is less about a single famous person than about the thousands of anonymous laborers, masons, and engineers who dug the channel and laid the stone. Canal building in this era was backbreaking work done largely by hand and with the help of animals — earth moved by shovel and cart, lock walls fitted block by block by skilled stonecutters.
What makes this site notable is a quirk of engineering. Where the land dropped sharply, canal builders sometimes grouped locks close together to manage the change in elevation over a short distance. Here, three locks and their connecting levels sat adjacent to one another — an unusual concentration that gave the place its name and made it a distinctive point along the line.
A boat working through such a stretch would have been a slow, deliberate affair: gates closing, water rising or falling, the craft easing forward to the next chamber. Multiply that patience across an entire mountain crossing and you begin to sense both the ingenuity and the limits of canal travel.
Its place in the American story
Pennsylvania's canal system was part of a wave of "internal improvements" that transformed the early United States. Before railroads, canals were the cutting edge of transportation — they slashed the cost of moving goods and helped bind a scattered, mostly rural nation into a single economy. Farmers could reach distant markets; manufactured goods could travel inland; towns grew up along the water route.
Yet the canals also tell a cautionary tale. They were spectacularly expensive to build and maintain, and their triumph was brief. Within a generation, the railroad — faster, cheaper to operate, and unhindered by winter ice — made the great canal systems obsolete. Pennsylvania's grand public work was eventually sold off and largely abandoned.
That rise and fall is a distinctly American arc: enormous public ambition, a burst of transformative usefulness, and then swift replacement by a newer technology. These quiet locks mark the exact spot where that story played out in stone.
If you visit
Come with an eye for the shape of the land and the work of hands. The old stonework and the traced bed of the canal are the main things to find — look for the straight, level channel that a river never cuts on its own, and for the fitted stone that marks where the lock walls once held back the water.
Stand for a moment and imagine the pace: a canal boat did not roar past, it inched through, chamber by chamber. The setting is peaceful now, but it was once a working artery, busy with boats and the shouts of lock-tenders.
This makes a rewarding stop on a slower drive through the Juniata valley, where the river, the old road, and the rail line still share the same narrow gap through the ridges. Pair it with a walk along the water, and let the quiet do the storytelling — this is a place that rewards standing still and reading the ground.
Written by AI to add context, grounded in the marker’s inscription and the historical record. The inscription above is the original, unaltered text.
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Nearby & related markers
Lewistown Station
Granville Township, PA · est. 1996
Built in 1848-49 as a freight warehouse, this is the oldest surviving structure known to have been raised by the mighty Pennsylvania Railroad — the company that would become one of the largest corporations on earth. Its opening was toasted at a banquet in September 1849 celebrating the rails' arrival in Lewistown, part of the great mid-century push to lace the state with iron. By 1868 the freight house had been remade into a passenger station, greeting travelers where goods once moved.
Mifflin County
Lewistown, PA · est. 1981
Established in 1789 from Cumberland and Northumberland counties, Mifflin County took its name from Thomas Mifflin, an early governor of the commonwealth. Its seat, Lewistown, was laid out the following year as settlers pushed into the Juniata Valley. In the decades that followed the county became important to Pennsylvania's canal era and its early iron industry, twin engines of the state's rise.
Travel History
Derry Township, PA · est. 1947
At this bend of the Juniata River, four generations of American movement stacked up in a single view: the old stone turnpike later paved over in concrete, the crumbling towpath and locks of a canal, the memory of river craft that once poled goods upstream, and the Pennsylvania Railroad cutting along the far bank. Each replaced the last as the nation's appetite for faster, cheaper transport reshaped the Appalachian valleys in the 1800s. The Juniata corridor was one of the great gateways west, and every mode of travel left its trace here.
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