Jefferson County, New York in the context of Fort Drum

Watertown is a city in and the county seat of Jefferson County, New York, United States. It is approximately 25 miles (40 km) south of the Thousand Islands, along the Black River, about 5 miles (8 km) east of where it flows into Lake Ontario. The city is bordered by the town of Watertown to the south, east, and west, and is served by the Watertown International Airport and the Watertown Daily Times newspaper. In the middle of Watertown lies the Public Square Historic District, which was built in 1805 and listed on the National Register of Historic Places (NRHP) in 1984. Watertown is located 13 miles (21 kilometers) southwest of the U.S. Army base at Fort Drum; it is the service and shopping destination for personnel there and their families. As of the 2020 United States census, the city has 24,685 residents, making it the largest city in the North Country.

The area was first surveyed in 1795, and was settled in March 1800 due to the abundant hydropower the Black River provided. The city was designated as the county seat of Jefferson County when it was split off from Oneida County in 1805. Watertown was incorporated as a village in 1816, and became a city in 1869. By then, it was booming as an industrial center for Upstate New York. During the mid 1960s, Chicago attracted many of the younger residents from the area along with their businesses, leading to the demolition of many historic buildings and a steady decline in population. By 2000, the city had lost over 7,000 residents.

The North Country of Upstate New York is the northernmost region of the U.S. state of New York. It is bordered by Lake Champlain to the east and further east to the adjacent state of Vermont and the New England region; the Adirondack Mountains / Adirondack Park and the Upper Capital District with the state capital of Albany to the south; the Mohawk Valley region of New York to the southwest; the Canadian-American international border (with the Province of Ontario in Canada) to the north; and Lake Ontario, (the eastern-most of the Great Lakes) and the Saint Lawrence River / Saint Lawrence Seaway, and beyond the waters again to Ontario / Canada to the west. A mostly rural forested area, the North Country includes seven counties (or 14, according to another group) of the 62 in New York state. Fort Drum, a United States Army base, is also located in the North Country region in Jefferson County, near Watertown, as is the adjacent Adirondack Park of 6.1 million acres, established 1892 as the oldest state park in the nation, and preserved / operated by the Adirondack Park Agency and the New York State Department of Environmental Conservation. As of 2024, the population of the region was 420,311 (revised figure from the last 2020 United States census).

The term "North Country" was first widely popularized within New York by the 1900 novel Eben Holden by Irving Bacheller.

The Black River is a 125-mile-long (201 km) blackwater river that empties into the eastern end of Lake Ontario on the shore of Jefferson County, New York in the United States. The origin of the name is not clear, but it may stem from the natural tannic acid that darkens the water in places. The river flows in a generally northwest direction, with its valley dividing the Adirondack Mountains on the east from the Tug Hill region to the west.

Watertown is a town in Jefferson County, New York, United States. The population was 5,913 at the 2020 census. The town is located in the central part of the county and borders the city of Watertown to the south, east, and west. As the city has a population of 24,685, or four times the town's population, references to "Watertown, New York", usually apply to the city rather than the town.

Watertown International Airport (IATA: ART, ICAO: KART, FAA LID: ART) is in the Town of Hounsfield in Jefferson County, New York, United States, 6 mi (5.2 nmi; 9.7 km) west of Watertown. The airport is used for general aviation, but has scheduled passenger service subsidized by the Essential Air Service program. The airport has no scheduled international passenger flights, but is available as an international port of entry for private aircraft on two hours' advance notice from pilots.

The Federal Aviation Administration says this airport had 2,203 passenger boardings (enplanements) in calendar year 2010, 4,449 in 2011, and 16,988 in 2012. It is included in the Federal Aviation Administration (FAA) National Plan of Integrated Airport Systems for 2023–2027, in which it is categorized as a non-hub primary commercial service facility.

List of the National Register of Historic Places listings in Jefferson County, New York

This is intended to be a complete list of properties and districts listed on the National Register of Historic Places in Jefferson County, New York. The locations of National Register properties and districts (at least for all showing latitude and longitude coordinates below) may be seen in a map by clicking on "Map of all coordinates".

Cape Vincent is a town in Jefferson County, New York, United States. The population was 2,765 at the 2020 census.

The town is in the northwestern part of the county. In the town is a village also called Cape Vincent. Both town and village are northwest of Watertown.