Once home to more than a dozen stone arch masonry bridges, Hillsborough now has five of these gems, four of which are used everyday to support auto, bike and foot traffic. These bridges are registered as historic structures by the Historic American Building Survey, part of the National Park Service. Most recently they have been recognized as a National Historic Civil Engineering Landmark, the second in New Hampshire, after the Cog Railway.
Stone arch bridges were a solution to the weakness of timber bridges and were especially suited for withstanding frequent flooding in the steeply sloping New Hampshire streams and rivers. Historical records reflect the repeated destruction and rebuilding of many of the earlier wooden bridges, leading townspeople to seek more rugged and enduring forms of construction.
At the time, lime mortar did not have sufficient strength to withstand the arch stresses, often failed to harden in the interior arch walls, and did not set in water. By a more careful cutting and fitting of stones, it was possible to make stronger stonework than could be made with use of the conventional lime mortar of the period; hence the development of the technique known as “dry masonry.”
The stone arched bridges are believed to have been the work of Scotch-Irish stonemasons who emigrated to Hillsborough in the 19th century. Selectmen Hiram Monroe argued that the bridges be built of stone to last, and that they have. Each of these lovely examples of bridge building craft is still in place with original keystones and held together without the benefit of mortar.
A brief tour by car or bike can take you to all of them, or a walking tour along the scenic Beard Brook will show you three of them. In warm weather, you can finish your tour with a refreshing dip in the Old Swimming Hole. A public beach, bathhouses and barbecue grills are available, along with ample parking.
The first bridge is the magnificent double arch bridge over the Beard Brook at the meeting of the Beard and Jones Roads, known as the Old Carr Bridge, built by Captain Jonathan Carr in 1840, and allegedly paid for with counterfeit money. This mortar-free graceful span breaches the brook and is a popular fly fishing spot.
North up Beard Road looms the mighty Gleason Falls Bridge, which contains an impressive cascade of water. Located near the junction of Gleason Falls and Beard Roads, this inviting spot offers picnicking, wading, and fishing. The falls rush under this venerable stone bridge from the 1840s, and are at their best in the spring.
Another fine stone span stands up the road and to the left on the Gleason Falls Road, at the site of one of the town’s first gristmills. This bridge is shrouded in mystery as to when it was built and by whom. The clever craftsman built a unique bridge, which actually consists of a causeway and two bridges over Beard Brook. The span to rise ratio of each arch is what makes this one unique. While most conventional arches would be semi-circular with a span to rise ratio of 2.0, as it is with one arch, the ratio of the other arch is a staggering 4.37!
Returning south down Beard Road, and across Rt. 9/West Main Street to the Saw Mill Road we come on the quaint stone bridge south of the Lower Village, a grouping of early houses, surrounded by forests, that is both rich in character and history. Saw Mill Road Intersects the Second NH Turnpike, which was once the main road from Claremont to the south.
To the left of this intersection you will find the bridge that was built in 1864 for $100. This bridge provided reliable transportation along the vital route from the northeast to Boston. This particular road was so important that an up-and-coming Benjamin Pierce built his fine new house and tavern on it. In that very house he raised a son who would go on to become a U.S. President; Franklin Pierce.
It is said that the finest Hillsborough stone arch bridge was built in 1866 by Rueben Loverin, known as the Sawyer Bridge. Despite some modifications made for commercial use, the bridge retains its integrity. It can be found at the junction of Route 202 and West Main Street, where it has had its traffic diverted and will soon be home to a small garden park for picnicking. This bridge once included a third arch more distanced from the other two, at its south end, which served as an opening allowing cattle to pass beneath and travel between the neighboring farm’s fields. In 1988, days before the bypass bridge was to open, the third arch collapsed, necessitating an earlier opening of the new bridge.
We hope you enjoy Hillsborough’s unique relics of New England’s history, and wish you many safe returns.
by Karen Johnson
Reprinted with permission from the Hillsborough Chamber of Commerce