New Haven and Northampton Canal

The New Haven and Northampton Canal was a major private canal built in the early 19th century to provide water transportation from New Haven into the interior of Connecticut and Massachusetts, ending in the Connecticut River at Northampton. Its Connecticut segment was known as the Farmington Canal and the Massachusetts segment the Hampshire and Hampden Canal.

Built in the decade after the opening of the original Erie Canal, the New Haven and Northampton Canal was one of the most significant civil engineering projects in the early 19th century United States and at 86 miles (138 km) New England's longest canal. The canal improved freight access for manufacturers and communities in the region during a critical period of the country's First Industrial Revolution. However, as a private venture it was a financial failure and only operated along its full extent from 1835 to 1847. With the advent of rail and steam locomotives, the canal company and right-of-way was quickly converted to a railroad, which was in more recent years converted to a rail trail. Few of the canal's original structures remain but short sections of canal bed and towpath survive as well as several locks.

During the early 19th century, the Connecticut River was the most efficient and commercially significant route into the interior of New England. Towns and cities along the river, such as Hartford, Connecticut, benefited from their position and access to water transport. However, Hartford's co-capital at the time, New Haven, relied on difficult overland access to the interior, and a canal had been considered since at least the 1780s. By the time the Erie Canal had begun operations canal enthusiasm was at its height. New Haven businessmen and town representatives met on January 29, 1822 in Farmington to hire the Erie's chief engineer, Benjamin Wright, to survey a route for a canal.

Wright hired Eli Whitney Blake to conduct a preliminary survey, and wrote a positive report: "The terrain is favorably formed for a great work of this kind and a canal may be formed for considerable less expense per mile, than the cost of canals now in the making in the state of New York." On May 30, 1822 the Connecticut legislature granted a charter to the "Farmington Canal Company" to build the canal from New Haven to the Massachusetts border. On February 4, 1823, Massachusetts granted its corresponding charter to the "Hampshire and Hampden Canal Company" from Southwick to Northampton. After this second charter was granted, work began.

A vastly more ambitious plan would have extended the canal north through the Connecticut River valley to Barnet, Vermont and on to Lake Memphremagog, where a Canadian company would build to the major shipping route of the St. Lawrence River via the Saint-François River. DeWitt Clinton Jr. of the United States Army Corps of Engineers surveyed several routes to link the Connecticut River and Memphremagog, including a very difficult and expensive route through the Black River Valley, Joe's Pond near Danville, and the Passumpsic River involving 350 locks and a 2-mile-long tunnel. An easier route followed the Barton River and Passumpsic River to Barnet. The proposal to extend the Hampshire and Hampden Canal was ultimately rejected by the Massachusetts legislature in favor of an initiative by competing "Riverites" to improve navigation along the Connecticut River itself.

Side canals were also envisioned, including one running from Farmington west through Unionville to Colebrook and the Massachusetts border, where it would link to the Erie Canal via the Hudson River or the proposed (but never built) Boston and Albany Canal.

Ground-breaking ceremonies took place on July 4, 1825 at Salmon Brook village in Granby near the Massachusetts–Connecticut border. Between two and three thousand spectators showed up and the Declaration of Independence was read by Timothy Pitkin. However, when Connecticut Governor Oliver Wolcott Jr. employed the ceremonial shovel, it broke. Built before the advent of steam shovels, the canal was graded and dug out with manual labor and the assistance of ox-drawn ploughs and draft horses. Techniques in earthmoving from the Erie were brought over to work on the new canal, including stump pullers which employed a giant windlass mechanism pulled by oxen. Buck scrapers or slip scrapers moved dirt similar to modern-day bulldozers.

In Connecticut, the Farmington Canal was built in sections by contractors according to specifications by canal engineers. Some larger individual features such as culverts, bridges, and the Farmington aqueduct were contracted out separately. In Massachusetts' Hampshire and Hampden Canal there were only two contracts. Although engineers and some laborers had come with experience from the Erie, local contractors were generally inexperienced in large-scale excavation and canal construction. As a result some work needed to be rehired or later redone. Though specifications may have called for rolled clay lining of the canal, much of it was unlined sandy soil which required subsequent relining in sections. Hydraulic lime sourced in Southington was later used to rebuild locks using masonry.