Jefferson County, New York

County seat: Watertown · Population 111,540 (2025) · 1,268 sq mi

Jefferson County is the 26th most populous of New York's 62 counties, with 111,540 people (2025 estimate). Its county seat is Watertown. The map shows its 20 cities and towns and the 4 neighboring counties.

Map of Jefferson County, New York with cities, towns and the county boundary
Jefferson County, New York with its cities and towns, unincorporated communities (CDPs) and neighboring counties. Boundaries: U.S. Census Bureau, 2025. Free to use with attribution (CC BY 4.0).
Download PDF (Letter) 136 KBPNG image 140 KBNew York county map

Jefferson County facts

County seat
Watertown
Population (2025 estimate)
111,540 −4.4% since 2020
Land area
1,268 sq mi 10th largest of 62
Water area
589 sq mi
Population density
88 per sq mi
Established
1805
Same name
One of 25 Jefferson Counties in the US
Named after
Thomas Jefferson Founding Father, U.S. president from 1801 to 1809 (1743–1826)
Largest city
Le Ray 24,259
Median household income
$66,301
Cities and towns
20 plus 21 CDPs
ZIP codes
43
Time zone
Eastern
FIPS code
36045

Cities and towns in Jefferson County

Jefferson County has 20 incorporated cities, towns and villages. Populations count the people living inside Jefferson County; cities that cross a county line also list the other counties.

NameTypePopulation 2025Also in
Watertown (county seat)City23,517
CarthageVillage3,196
West CarthageVillage1,721
ClaytonVillage1,656
AdamsVillage1,636
Sackets HarborVillage1,337
Black RiverVillage1,208
PhiladelphiaVillage1,125
DexterVillage989
Alexandria BayVillage922
BrownvilleVillage911
TheresaVillage727
Cape VincentVillage713
Evans MillsVillage604
ChaumontVillage581
AntwerpVillage503
Glen ParkVillage436
MannsvilleVillage318
DeferietVillage247
EllisburgVillage207

Unincorporated communities (CDPs)

Census-designated places are communities without their own city government; the county provides their services.

CommunityPopulationAlso in
Fort Drum16,065
Calcium2,935
Adams Center1,075
Great Bend938
Pamelia Center907
La Fargeville512
Pierrepont Manor425
Felts Mills402
Redwood371
Depauville310
Thousand Island Park222
Belleville220
Rodman220
Henderson207
Plessis176
Lorraine107
Oxbow92
Fishers Landing91
Natural Bridge91
Three Mile Bay44
Herrings0

ZIP codes in Jefferson County

43 ZIP codes reach into Jefferson County. ZIP codes ignore county lines, so some also cover a neighboring county.

Population of Jefferson County, 2020–2025

Jefferson County shrank by 5,170 people (−4.4%) between April 2020 and July 2025: 3,450 more births than deaths and a net loss of 8,683 people from migration.

Year (July 1)Population
2020116,075
2021117,019
2022115,493
2023113,280
2024112,795
2025111,540

Neighboring counties

Printable Jefferson County map

The PDF is a vector file with real text: it prints sharp on Letter paper and you can search it for a town. The PNG is 2400 pixels wide for slides and documents. Both are free to use with a credit to WhichCounty.

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Sources

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