The Contoocook Railroad Bridge is a covered bridge on the former Contoocook Valley (first Concord & Claremont, later Boston & Maine) Railroad line spanning the Contoocook River in the center of the village of Contoocook, Merrimack County, New Hampshire.

Built in the 19th century, it is the oldest extant covered railroad bridge in the United States and served rail traffic until 1960. It was used as a warehouse until 1989, then became public property, and has been preserved by the state, donations, and volunteers, in association with the nearby historic railroad depot.

Re-built in 1889 to replace a lighter-covered railroad bridge constructed between 1849–50, having been built by the former Concord and Claremont Railroad (acquired by the Boston & Maine Railroad in 1887), the bridge is the oldest of four surviving double-web Town lattice railroad bridges, and is the oldest extant covered railroad bridge in the United States. (The other double Towns are Pier Bridge, Newport, New Hampshire, 1907; Wright's Bridge, Newport, NH, 1906; and Fisher Bridge, Stowe, Vermont, 1908.) It was probably designed by Boston & Maine Railroad engineer Jonathan Parker Snow (1848–1933) and built by carpenter David Hazelton (1832–1908). Under Snow, Boston & Maine utilized wooden bridges on its branch lines longer than any other major railroad, the last of these constructed in 1916. The nearby Contoocook Railroad Depot was built in 1850 on the earlier Concord & Claremont Railroad.

The bridge presents the clearest, most original structure of its type, as the others incorporate significant structural modifications. The main trusses are double Town lattice and are continuous over a central pier to form two spans of approximately 71 feet each. It has been often said they were built by the mile and cut off by the yard. The center pier is skewed to match the river flow, as are the abutments. This is because the bridge spans the river on a bias.

The bridge was in use as a railroad bridge until 1962, survived a flood in 1936, a hurricane in 1938, and was moved off its foundations twice during its lifespan and saved from being completely washed downriver by the rail tracks running through it. Following its railroad service, it functioned as a warehouse between 1962 and 1990.

In 2006 the bridge saw minor structural repairs to its bottom chord at the upstream north corner, the bolsters were replaced for the first time since the hurricane of 1938, and the bed timbers were replaced by granite pedestals. The work was paid for by a donation from the National Society for the Preservation of Covered Bridges.

The bridge underwent slight alterations being completed mid-winter 2009-2010 which consisted of a dry-head, open pipe sprinkler system for the bridge interior with exterior fire department connection, including linear heat detectors, fire alarm system, fire retardant coating, and LED motion sensor lighting inside the bridge at an approximate cost of $123,300 paid for and engineered by the New Hampshire Department of Transportation.

In April 2019, bridgework to stain the bridge and make minor repairs took place. The project was funded by the state's "Moose Plate" grant program. Volunteers from the town's 250th-anniversary committee as well as the Contoocook Riverway Association had dedicated time and efforts to see the project through.

Of the 400 covered bridges that once stood in the state of New Hampshire, as of 2019 only 54 remain.

It is referred to in the National Register of Historic Places as the Hopkinton Railroad Covered Bridge, for the town of Hopkinton, New Hampshire, in which the village of Contoocook is located.

Located at:  N43 13.385    W71 42.834     -     WGCB #29-07-07

Photographed in July of 2019.