a town of the United States of North America, state of New York, on both sides of the Saranac, at its mouth in a wide and beautiful bay on Lake Champlain, 160 miles N. by E. of Albany. It contains many good edifices, among which are the county buildings, several churches, an academy and other schools, two banks, &c. There are also saw-mills, cotton factories, and manufactories of leather, machinery, &c. Plattsburg is a military post, and a large stone barracks was recently erected in the neighbourhood, but it is not at present garrisoned. An extensive and active trade is carried on, the town being connected by railway with Montreal, and by steamers with the various other ports on the lake. The tonnage of the port, enrolled and licensed, June 30, 1852, was 6259; of which, sailing-vessels 4558 tons, steamers 1701 tons. Pop. (1850) 5618.