PLATTSBURGH, a village and township of the United States, the shire-town of Clinton county, New York, and the port of entry of Champlain customs district, lies on the west side of Lake Champlain at the mouth of the Saranac. By rail it is 168 miles north of Albany and 73 south-south-east of Montreal (Canada). A branch line runs 20 miles south-west to Au Sable and forms a favourite route to the Adirondacks, and the Chateaugay Railroad runs 34 miles west by north to Lyon Mountain, where there are extensive iron mines. Plattsburgh contains county buildings and court-house, a custom-house, a high school, and a small public library. It has nail and avaggon factories, flour-mills, saw-mills, an iron furnace, machine shops, and a large sewing-machine manufactory. It is a garrison town of the United States army, with extensive barracks about a mile south of the village. The value of the imports and exports of the district for the year ending June 30th 1884 was $3,169,780 and $1,319,422; and 1279 vessels entered from Canada, while 1179 cleared. The aggregate burthen of the vessels belonging to the district was 57,477 tons. In 1870 the township had 8414 inhabitants, the village 5139; in 1880 the figures were 8283 and 5245.

Plattsburgh dates from 1785. It has twice been destroyed by fire (1849 and 1867). In 1812 it became the headquarters of the U.S. army on the northern frontier; and in September 1814 it was rendered famous through the capture of the British flotilla under Commodore Downie by the United States flotilla under Commodore Macdonough, and the consequent retreat across the Saranac of Sir George Prevost, who had been attacking the village with a powerful army. Downie and fifteen other officers of the contending forces are buried in Plattsburgh cemetery.