2020-05-04: 1937 NH-Vt bridge named to National Register of Historic Places2020-05-05T08:49:04-04:00


Shelly Angers, N.H. Department of Natural & Cultural Resources
Twitter: @NHDNCR

1937 NH-Vt bridge named to National Register of Historic Places

The New Hampshire Division of Historical Resources has announced that the Lyme-East Thetford Bridge has been honored by the United States Secretary of the Interior with placement on the National Register of Historic Places for its role in interstate transportation and as one of only two bridges of its type in New Hampshire.

Built in 1937 in the midst of the Great Depression, the Lyme-East Thetford Bridge connects the towns of Lyme, N.H., and East Thetford, Vt., across the Connecticut River, which forms the border between the two states.

The site’s long history as a crossing between the two communities was first documented as a ferry landing in 1780. An 1840s bridge provided Lyme residents with access to the railroad in East Thetford; a second bridge, built in the mid-1890s, was destroyed during a flood in 1936 when large cakes of ice knocked out its middle section.

At 471 feet, the Lyme-East Thetford Bridge is the longest two-span Parker Truss bridge in New Hampshire.

Charles H. Parker’s original design for metal bridges incorporated a bowstring arch. The arch on Parker truss bridges is variation of flat-topped Pratt truss bridges, commonly used for railroads. Most moderate- to long-span highway bridges built in New Hampshire during the 1920s and 1930s adopted the Parker truss design.

Begun in February 1937, the Lyme-East Thetford Bridge was built when changes in steel rolling technology made it possible to use sectional beams, making truss bridge construction faster and less expensive. Steel components and other elements for the bridge were shipped by rail to East Thetford.

American Bridge Company, a subsidiary of J.P. Morgan’s United States Steel Company, fabricated steel components for the bridge. The company was the contractor for the original Memorial Bridge between Portsmouth, N.H., and Kittery, Maine, and worked on projects nationwide, including the Oakland Bay Bridge and the Empire State Building.

A mid-river reinforced concrete pier as well as the bridge’s abutments rest on 12-foot steel piles driven into the river bottom. In an effort to avoid the destructive flooding that destroyed earlier bridges at the site, each is higher than substructures on the previous bridge.

The engineer who designed the substructure, Gordon Whittum, was also a construction engineer on the Cannon Mountain Aerial Tramway.

The Works Progress Administration provided most of the funding for the Lyme-East Thetford Bridge. The WPA had little hands-on involvement with New Hampshire flood bridges but did require compliance with minimum standards such as right-of-way width. By October 1936, more than 200 WPA flood projects in New Hampshire were completed, nearing completion, had received approval or were ready to start. 

The Lyme-East Thetford Bridge was placed on the N.H. Department of Transportation’s “red list” of bridges in 2013, requiring it to be inspected twice a year.

Administered by the National Park Service, which is part of the U.S. Department of the Interior, the National Register of Historic Places is the nation’s official list of historic resources worthy of preservation and is part of a national program to coordinate and support public and private efforts to identify, evaluate and protect our historic and archaeological resources.

Listing to the National Register does not impose any new or additional restrictions or limitations on the use of private or non-federal properties. Listings identify historically significant properties and can serve as educational tools and increase heritage tourism opportunities. The rehabilitation of National Register-listed commercial or industrial buildings may qualify for certain federal tax provisions.

In New Hampshire, listing to the National Register makes applicable property owners eligible for grants such as the Land and Community Heritage Investment Program or LCHIP (lchip.org) and the Conservation License Plate Program (nh.gov/nhdhr/grants/moose).

For more information on the National Register program in New Hampshire, please visit nh.gov/nhdhr or contact the Division of Historical Resources at 603-271-3583.

New Hampshire’s Division of Historical Resources, the State Historic Preservation Office, was established in 1974 and is part of the N.H. Department of Natural and Cultural Resources. NHDHR’s mission is to preserve and celebrate New Hampshire’s irreplaceable historic resources through programs and services that provide education, stewardship, and protection. For more information, visit us online at nh.gov/nhdhr or by calling 603-271-3483.