Editing Middlesex Canal (section)

{{Short description|Barge canal in eastern Massachusetts, US}}
{{Use American English|date=January 2025}}
{{Use mdy dates|date=August 2023}}
{{Infobox NRHP
| name         = Middlesex Canal
| nrhp_type    = hd
| nocat        = yes
| image        = Shawsheen River Aqueduct, Middlesex Canal, Massachusetts.JPG
| caption      = Remnants of the [[navigable aqueduct|aqueduct]] that carried the canal over the [[Shawsheen River]] on the [[Billerica, Massachusetts|Billerica]]-[[Wilmington, Massachusetts|Wilmington]] town line
| location     = [[Lowell, Massachusetts|Lowell]]-[[Woburn, Massachusetts]] (surviving fragments)
| locmapin     = Massachusetts#USA
| built        = {{start date|1803}}
| architect    = [[Loammi Baldwin]]; [[James Sullivan (governor)|James Sullivan]]
| architecture =
| added        = August 21, 1972
| area         = {{convert|245|acre|ha}}
| refnum       = 72000117<ref name="nris">{{NRISref|version=2010a}}</ref>
}}

The '''Middlesex Canal''' was a 27-mile (44-kilometer) [[barge]] [[canal]] connecting the [[Merrimack River]] with the port of [[Boston, Massachusetts|Boston]]. When operational it was 30 feet (9.1 m) wide, and 3 feet (0.9 m) deep, with 20 locks, each 80 feet (24 m) long and between 10 and 11 feet (3.0 and 3.4 m) wide. It also had eight aqueducts.

Built from 1793 to 1803, the canal was one of the first [[civil engineering]] projects of its type in the [[United States]], and was studied by engineers working on other major canal projects such as the [[Erie Canal]]. A number of innovations made the canal possible, including [[hydraulic cement]], which was used to mortar its locks, and an ingenious floating [[towpath]] to span the [[Concord River]].  The canal operated until 1851, when more efficient means of transportation of bulk goods, largely railroads, meant it was no longer competitive.

In 1967, the canal was designated a [[National Historic Civil Engineering Landmark]] by the [[American Society of Civil Engineers]]. Remnants of the canal still survive and were the subject of a 1972 listing on the [[National Register of Historic Places]], while the entire route, including parts that have been overbuilt, is the subject of a second listing in 2009.