Middlesex Canal | |
 Remnants of the aqueduct that carried the canal over the Shawsheen River on the Billerica-Wilmington town line | |
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| Location | Lowell-Woburn, Massachusetts (surviving fragments) |
|---|---|
| Area | 245 acres (99 ha) |
| Built | 1803 |
| Architect | Loammi Baldwin; James Sullivan |
| NRHP reference No. | 72000117[1] |
| Added to NRHP | August 21, 1972 |
The Middlesex Canal was a 27-mile (44-kilometer) barge canal connecting the Merrimack River with the port of 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.