Formed January 1, 1805 (34th county)
Jefferson County (116,723), Watertown (24,670)
A 2000 masonry and glass Modern structure sits on Arsenal Street at Arcade Street. New York State Highway 12 passes in front of the courthouse. The architect is unknown. A County Administrative building supports the courthouse. The old 1964 Post Office building was purchased and connected to the courthouse. The county was organized on January 1, 1805 from Oneida County as the 34th county with Watertown as the only county seat. The county is named for United States President Thomas Jefferson. Watertown is named for its geographical location on Black River Falls. Jefferson County was the birthplace for 1 New York Governor, Roswell P. Flower.
Jefferson County government consists of an administrator, a sheriff, a comptroller, an attorney, an assessor, and a clerk (executive). It has 15 Legislators (legislative.) One County Court Judge, One Family Court Judge, and One Surrogate Court Judge serve Jefferson County (judicial.) The county is in the northwest corner of the state. Albany, New York is southeast and Buffalo, New York is southwest of the county. Canada is on its western border. The county center is 8.6 miles Northwest of Watertown nearer Brownville. The county is surrounded clockwise by Saint Lawrence, Lewis, and Oswego counties, and Canada.
The area of the county is 1857 square miles. It is 4 out of 62 in the state. It ranks 25 out of 62 in population in the state. It has a density of 62.9 persons per square mile making it 48 out of 62 in the state. Jefferson County has 38.1% of its population in its incorporated areas. Interstate Highway 81 originates in the county and travels south into Oswego County. United States Highway 11 parallels Interstate Highway 81 from Saint Lawrence County to Oswego County. The county looks like a lion’s head. Watertown is located in the southern third of the county. Watertown is the county seat and the largest city. It is 21.1% of the county population. This county is in the Watertown-Fort Drum Micropolitan Statistical Area.
Adams
Alexandria Bay
Antwerp
Black River
Brownville
Cape Vincent
Carthage
Chaumont
Clayton
Deferiet
Dexter
Ellisburg
Evans Mills
Glen Park
Herrings
Mannsville
Philadelphia
Sackets Harbor
Theresa
Watertown
West Carthage