canal ceased operation its infrastructure quickly fell into disrepair. In 1852 the company ordered dilapidated bridges over the canal torn down and the canal underneath filled in. Permission was given for the company to liquidate and pay the proceeds to the stockholders, and its 1793 charter was revoked in 1860. The company's records were given over to the state for preservation. The canal corporation's land and dam in North Billerica, as well as the water rights on the Concord River, were sold to Charles and Thomas Talbot, who erected the Talbot Mills complex that now stands in the Billerica Mills Historic District. Parts of the canal bed were covered by roads in the 20th century, including parts of the Mystic Valley Parkway in Medford and Winchester, and parts of Boston Avenue in Somerville and Medford. Boston Avenue crosses the Mystic River where the canal did. Parts of the canal in eastern Somerville were filled in by leveling Ploughed Hill in the late 19th century. Ploughed Hill was the site of notorious anti-Catholic riots in 1832 and had subsequently been abandoned. Impact The opening of the canal diminished the commercial viability of the port of Newburyport, Massachusetts, the outlet of the Merrimack River, since all trade from the Merrimack Valley in New Hampshire now went via the canal to Boston, rather than through the sometimes difficult to navigate river. The canal also played a prominent role in the eventual growth of Lowell as a major industrial center. Its opening brought on a decline in business at the Pawtucket Canal, a transit canal opened in the 1790s which bypassed the Pawtucket Falls just downstream from the Middlesex Canal's northern end. Its owners converted the Pawtucket Canal for use as a power provider, leading to the growth of the mill businesses on its banks beginning in the 1820s. The Middlesex Canal was used for the transport of raw materials, finished goods, and personnel to and from Lowell. The canal's use of the Concord River had significant long-term environmental consequences. The raising of the dam height at North Billerica was believed to cause flooding of seasonal hay meadows upstream and prompted numerous lawsuits against the canal proprietors. These were all ultimately unsuccessful, due in part to the uncertainty of the science, and also in part to the political power of the proprietors. As the canal was in decline in its later years, the state