Merrimack grew into prominence; and, in 1792, Dudley A. Tyng, William
Coombs, and others, of Newburyport, were incorporated as "The
Proprietors of the Locks and Canals on Merrimack River." This canal,
which was demanded for the safe conduct of rafts by the Falls, was
completed in 1797, at an expense of fifty thousand dollars. The fall of
thirty-two feet was passed by four sets of locks.

The first bridge across the Merrimack was built, in 1792, by Parker
Varnum and associates; the Concord had been bridged some twenty years
earlier.

[Illustration: DAM AT PAWTUCKET FALLS.]

In 1793, the proprietors of the Middlesex Canal were incorporated.
Loammi Baldwin, of Woburn, superintended the construction. The canal
began at the Merrimack, about a mile above Pawtucket Falls, extended
south by east thirty-one miles, and terminated at Charlestown. It was
twenty-four feet wide and four feet deep and was fed by the Concord
River. It cost $700,000, and was completed in 1804,--the first canal
in the United States opened for the transportation of passengers and
merchandise. For forty years it was the outlet of the whole Merrimack
valley north of Pawtucket Falls.

The first boat voyage from Boston, by the Middlesex Canal and the
Merrimack River, to Concord, New Hampshire, was made in 1814; the first
steamboat from Boston reached Concord in 1819.

The competition of the Middlesex Canal ruined the Pawtucket Canal, as it
in turn, in after years, was ruined by the Boston and Lowell Railroad.
Navigation finally ceased on its waters in 1853, since which date its