Hamilton County, Ohio

Hamilton County is a county in Ohio, United States, in the state’s southwestern corner where
the Great Miami and Little Miami rivers meet the Ohio River at Cincinnati. It had a population of
830,639 at the 2020 census, an estimated 838,418 by 2024, and covers 413 square miles (1,070 km2)
centred near 39°12′N 84°32′W.

Cincinnati is the county seat and by far its largest city; its postal code is 45202. The county
holds 19 cities, 19 incorporated villages and roughly 50 unincorporated communities across 12
townships, and it runs on Eastern Time. Its FIPS code is 39061.

Towns & Villages in Hamilton County

Hamilton County has 38 incorporated cities and villages — more than any other Ohio county
— plus dozens of unincorporated census-designated places (CDPs) that never became independent
municipalities; several now function as Cincinnati neighborhoods in everything but legal status.
CDP stands for census designated place; Unincorp. covers places with no Census Bureau population
count of their own. Because Ohio incorporated cities and villages sit outside township government
once they incorporate, the Township column below is left blank for them and used only for the
unincorporated places that still fall under township jurisdiction.

Beyond the 38 incorporated places, Hamilton County has about 49 census-designated places —
unincorporated communities the Census Bureau tracks separately even though they have no city
government of their own. The eleven largest are:

Roughly 38 more CDPs and small unincorporated communities exist across the county, mostly
subdivisions and crossroads too small for the Census Bureau to publish a separate population
figure. Three names on the incorporated list are only partly in Hamilton County: Fairfield and
Loveland each sit mostly in Butler and Clermont/Warren counties, and Milford is mostly in Clermont
County — only small annexed edges of each reach into Hamilton, so their populations are
counted with their home counties, not here. Covedale, once a separate village, was annexed into
Cincinnati in 1930 and is now a Cincinnati neighborhood rather than its own CDP.

Townships

Hamilton County has 12 civil townships. Ohio townships lose jurisdiction over any land that
incorporates as a city or village, so several — especially Sycamore, which now exists as
three separated “islands” between Blue Ash, Montgomery and Reading — cover far
less ground than their names suggest.

ZIP Codes

• 45202 — downtown Cincinnati (one of roughly 40 ZIPs the city itself uses, in the 452xx
  range)
• 45240 — Forest Park
• 45212 — Norwood
• 45241 — Sharonville and Evendale
• 45242 — Blue Ash and Montgomery
• 45030 — Harrison
• 45246 — Springdale
• 45243 — Madeira and Indian Hill
• 45215 — Wyoming, Lockland and Lincoln Heights
• 45236 — Deer Park and Silverton

Most of the county’s smaller villages and every CDP share a ZIP with the nearest
incorporated town rather than carrying one of their own; Cincinnati alone administers dozens of
additional 452xx codes not listed above, one for most of its named neighborhoods.

Geography

Hamilton County sits at the southwestern tip of Ohio, where the Ohio River forms the entire
southern border with Kentucky. The Great Miami River marks most of the western edge and the
Little Miami River crosses the eastern side near Newtown. Of the county’s 413 square miles,
406 are land and 6.7 are water, about 1.6 percent — low for a river county, since most of
that water is the Ohio River itself rather than inland lakes. The largest lake entirely within the
county is at Winton Woods, a Hamilton County park in Springfield Township built around a reservoir
dam completed in 1948.

Butler County lies to the north and Warren County to the northeast. Clermont County borders the
county on the east. Across the Ohio River to the south and southwest lie three Kentucky counties:
Campbell, Kenton and Boone. Dearborn County, Indiana, lies to the west and Franklin County,
Indiana, to the northwest. Butler
County, Warren County, Clermont County, Campbell County, Kenton County, Boone County, Dearborn County and Franklin County all border
Hamilton directly.

Demographics

Hamilton County had a population of 830,639 at the 2020 census, the third-highest count of any
Ohio county, and the latest estimate puts it near 838,418 residents by 2024. Cincinnati and Forest
Park are the two largest incorporated places, though White Oak and Bridgetown, both unincorporated,
outrank most of the county’s smaller cities. Median household income for the county was
$66,878 (2016–2020 American Community Survey), close to Ohio’s 2023 ACS state figure of
$67,769. Population density works out to roughly 2,046 people per square mile of land, the second
densest county in Ohio after neighboring Franklin County, Ohio’s home.

Economy & Local Life

Cincinnati anchors the county’s economy as headquarters city for Kroger and Procter
& Gamble, two of the country’s largest consumer companies, along with Fifth Third Bank.
GE Aerospace runs a major jet-engine plant in Evendale, and Ford Motor Company’s Sharonville
Transmission Plant, in operation since 1958, employs about 2,043 workers on 182 acres. Kroger also
keeps regional offices in Springdale, near Tri-County Mall, and Kenwood’s Kenwood Towne
Centre serves as one of the region’s largest shopping destinations. The University of
Cincinnati and Cincinnati Children’s Hospital Medical Center are both major employers within
the city itself. The county’s biggest recurring event is the Hamilton County Fair, the oldest
county fair in Ohio, and Cincinnati’s own Oktoberfest Zinzinnati draws large crowds downtown
each September.

History

The Northwest Territory’s governor, Arthur St. Clair, organized Hamilton County on
2 January 1790, thirteen years before Ohio joined the Union, and named it for Alexander Hamilton,
the first U.S. Secretary of the Treasury. Cincinnati, founded in 1788 and incorporated as a city in
1819, has served as the county seat from the start. The county reached its highest recorded
population in the 1970 census and has declined modestly since, even as some of its suburbs, such
as Blue Ash and Sharonville, kept growing.

North Bend, on the Ohio River in the county’s far west, was home to President William
Henry Harrison and is the birthplace of his grandson, President Benjamin Harrison; both are
commemorated at the William Henry Harrison Tomb State Memorial. Reading, an inner suburb, was
documented as a sundown town as late as 1912, a history the village does not hide from its
records.

Getting There

Interstates 71, 74 and 75 all converge in downtown Cincinnati, with I-275 forming a beltway
around the entire metro area and I-471 crossing into Kentucky. US Routes 22, 27, 42, 50, 52 and 127
also cross the county.

• Cincinnati (downtown) — the county’s center
• Dayton — about 50 miles north
• Columbus — about 100 miles northeast
• Louisville — about 100 miles southwest

Cincinnati/Northern Kentucky International Airport (CVG), across the Ohio River in Boone County,
Kentucky, is the region’s major commercial airport. Amtrak’s Cardinal stops at
Cincinnati Union Terminal, connecting west to Chicago and east to Washington, D.C.

Frequently Asked Questions

Where is Hamilton County located?
It sits in Ohio’s southwestern corner on the Ohio River, bordered by Butler, Warren and
Clermont counties in Ohio, three Kentucky counties across the river, and two Indiana counties to
the west.

What is the population of Hamilton County?
830,639 at the 2020 census, with a 2024 estimate near 838,418.

How big is Hamilton County?
413 square miles (1,070 km2), of which 406 square miles are land.

What is the county seat of Hamilton County?
Cincinnati is the county seat and largest city.

How many towns and cities are in Hamilton County?
38 incorporated cities and villages, plus about 49 unincorporated CDPs including White Oak,
Bridgetown and Finneytown.

What ZIP codes does Hamilton County use?
Cincinnati alone uses roughly 40 codes in the 452xx range; suburbs include 45242 (Blue Ash,
Montgomery), 45241 (Sharonville, Evendale) and 45030 (Harrison).

What is Hamilton County known for?
Cincinnati’s riverfront downtown, the headquarters of Kroger and Procter & Gamble, and
North Bend, birthplace of President Benjamin Harrison.

More counties in this state: Towns and villages in Ohio.