Hamilton County, Indiana

Hamilton County is a county in Indiana, United States, about 20 miles north of Indianapolis. It
had a population of 347,467 at the 2020 census, an estimated 387,036 by 2025, and covers 394.27
square miles (1,021.2 km2) centred near 40°04′N 86°03′W.

Noblesville is the county seat; its postal code is 46060. The county holds 4 cities, 4
incorporated towns and several census-designated and unincorporated communities across 9
townships, and it runs on Eastern Time. Its FIPS code is 18057.

Towns & Villages in Hamilton County

Hamilton County has 12 named places on record: 4 cities, 4 incorporated towns, 3 census
designated places and one long-standing unincorporated community. Carmel, not the county seat, is
the county’s largest city. CDP stands for census designated place, a Census Bureau boundary
with no local government of its own; Unincorp. covers a settlement with no formal boundary at
all.

Riverwood, Hortonville and Boxley were only delineated as census-designated places in the 2022
American Community Survey, after the 2020 count, so none carries an official 2020 population
figure. Home Place, an older unincorporated community in Clay Township, is not listed separately
— Carmel annexed it on 1 March 2018 and it now returns Carmel addresses and ZIP codes.
Sheridan itself changed status on 1 January 2025, when voters approved consolidating the town’s
government with Adams Township; it remains a distinct place on this list because its ZIP code and
settlement identity are unchanged.

Townships

Civil townships still handle local government functions such as fire protection and township
assistance across Hamilton County, even inside the cities.

Fishers is split between Delaware and Fall Creek townships, which is why the city’s population
does not match either township figure on its own.

ZIP Codes

• 46060 — Noblesville (also 46061 and 46062, both Noblesville PO box ZIPs)
• 46032 — Carmel
• 46033 — Carmel
• 46074 — Westfield (also serves part of Carmel)
• 46038 — Fishers
• 46037 — Fishers
• 46034 — Cicero
• 46069 — Sheridan
• 46030 — Arcadia
• 46031 — Atlanta

Riverwood, Hortonville, Boxley and Strawtown have no ZIP code of their own; mail there is
delivered under the nearest incorporated town’s code.

Geography

Hamilton County sits in Indiana’s central till plain, flat to gently rolling farmland cut by
the White River, which runs north to south through the county’s middle. Of its 402.44 square
miles, 394.27 are land and 8.17 are water, about 2 percent — most of it Morse Reservoir, a
1,485-acre lake near Cicero built in 1956 as a water-supply reservoir, and Geist Reservoir, which
the county shares with Marion County along its southeastern edge.

Tipton County lies to the north, Madison County to the east, Hancock County to the southeast,
Marion County to the south, Boone County to the west and Clinton County to the northwest. Tipton County, Madison County, Hancock County, Marion County, Boone County and Clinton County all border Hamilton
directly.

Demographics

Hamilton County had a population of 347,467 at the 2020 census, and the latest estimate puts
the county near 387,036 residents by 2025. Carmel and Fishers are the two largest communities,
together holding well over half the county’s population even though neither is the county
seat. Median household income runs $121,530 as of 2024, according to Data USA, well above
Indiana’s 2023 statewide figure of $69,477 — Hamilton is regularly ranked the
highest-income county in Indiana. Population density works out to roughly 881 people per square
mile of land, among the densest counties in the state outside Marion County itself.

Economy & Local Life

Health care and social assistance employs the most workers in the county, about 30,326 people,
followed by professional, scientific and technical services at 24,225 and manufacturing at
21,521. Hamilton Southeastern Schools, based in Fishers, is the county’s single largest
employer at roughly 2,626 staff. Westfield’s Grand Park Sports Complex, the largest youth
sports campus in the United States with 26 baseball and softball diamonds and 31 multipurpose
fields, has hosted the Indianapolis Colts’ summer training camp since 2018 and draws more
than 5.5 million visits a year. Noblesville is home to Ruoff Music Center, the Indianapolis
area’s main outdoor concert venue since 1989, and Fishers opened a $170 million event center
in November 2024 that now hosts the ECHL’s Indy Fuel hockey team. The county’s biggest
annual event is Carmel’s Christkindlmarkt, an open-air German-style Christmas market held
each November and December that draws more than 400,000 visitors.

History

Indiana’s General Assembly formed Hamilton County on 8 January 1823, naming it for
Alexander Hamilton, the first U.S. secretary of the treasury. William Conner and Josiah Polk
established Noblesville that same year as the county seat, and it was incorporated as a town in
1851; accounts differ on whether the name honors Senator James Noble or a woman named Lavina
Noble, to whom Polk was reportedly engaged.

The county’s population stayed modest through the 19th and most of the 20th century,
climbing sharply only after 1990 as Indianapolis suburbs pushed north; Noblesville alone grew from
28,590 residents in 2000 to 51,969 by 2010. Noblesville also carries a difficult chapter of
Indiana history: the 1925 trial of Ku Klux Klan leader D.C. Stephenson, held in the county
courthouse, produced a conviction that broke the Klan’s political power across the state. On
1 January 2025, Sheridan completed a voter-approved consolidation of its town government with
Adams Township, one of the more unusual local-government changes in the county’s recent
history.

Getting There

Interstate 69 crosses the county through Fishers and Noblesville. US 31 and US 421 run
north-south through the county, along with State Roads 19, 32, 37, 38, 47 and 213.

• Indianapolis — about 20 miles south
• Anderson — about 20 miles east
• Kokomo — about 30 miles northwest
• Muncie — about 35 miles east

Indianapolis Metropolitan Airport, a general-aviation field in Fishers, serves the county
directly. Indianapolis International Airport, roughly 30 miles southwest of Noblesville, is the
nearest major commercial airport. Hamilton County has no Amtrak station; the nearest is
Indianapolis Union Station, about 25 miles south.

Frequently Asked Questions

Where is Hamilton County located?
It sits in central Indiana’s till plain, about 20 miles north of Indianapolis, bordered by
Tipton, Madison, Hancock, Marion, Boone and Clinton counties.

What is the population of Hamilton County?
347,467 at the 2020 census, with an estimate near 387,036 by 2025.

How big is Hamilton County?
394.27 square miles (1,021.2 km2) of land, part of a 402.44-square-mile total that includes 8.17
square miles of water.

What is the county seat of Hamilton County?
Noblesville, founded in 1823, is the county seat, though Carmel is the county’s largest
city.

How many towns and cities are in Hamilton County?
Four cities — Carmel, Fishers, Noblesville and Westfield — plus four incorporated
towns: Cicero, Sheridan, Arcadia and Atlanta.

What ZIP codes does Hamilton County use?
46060 to 46062 for Noblesville, 46032 and 46033 for Carmel, 46037 and 46038 for Fishers, 46074 for
Westfield, 46034 for Cicero, 46069 for Sheridan, 46030 for Arcadia and 46031 for Atlanta.

What is Hamilton County known for?
Being Indiana’s highest-income county, Westfield’s Grand Park Sports Complex, and
Carmel’s roundabout network of more than 150 intersections.

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