When was Hamilton County founded?

Hamilton County was founded in 1823, formed from Delaware County, Adams County and Marion County, and named after Alexander Hamilton.

What is the county seat of Hamilton County?

The county seat of Hamilton County is Noblesville.

Is there an online parcel map for Hamilton County?

Yes. Indiana Geographic Information Office (IndianaMap) publishes a parcel map of 150,707 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.

Has Hamilton County's boundary or name changed?

Hamilton County was created in 1823 from Delaware County, Adams County and Marion County. Since then the Atlas of Historical County Boundaries records 9 later changes, chiefly involving Adams County, Delaware County and Tipton County.

Who issues building permits in Hamilton County?

The county's page on building permits: Permits and Applications. Inside a city or town, ask that city first.

Who issues septic and well permits in Hamilton County?

The county's page on septic systems and wells: Health department: septic and well.

Is my lot in a flood zone?

We do not have flood maps for Hamilton County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

County · code 18057

Hamilton CountyIndiana

Hamilton County is a county in Indiana with its seat in Noblesville. It was established on April 7, 1823, from parts of Delaware, Adams, and Marion Counties and named after Alexander Hamilton.

Founded1823
County seatNoblesville
Named forAlexander Hamilton
Land area394 sq mi + 8.1 sq mi water
Population347,467 2020 Census
Parcels mapped150,707 checked 15 October 2026

Open the free map Click any parcel in Hamilton County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated 19 October 2026

Census outline · seat marked

History

Formed in 1823 from Delaware County, Adams County and Marion County

An old deed may name a county that no longer exists, or a boundary that has since moved.

Hamilton County was created from the unattached part of Delaware New Purchase (later Adams New Purchase) and from part of Delaware New Purchase attached to Marion. Over the following decades, the county experienced numerous boundary adjustments as parts of Adams New Purchase and other areas were attached to or detached from it for administrative and judicial purposes, with attachments and detachments involving neighboring counties including Delaware, Madison, Hendricks, Tippecanoe, Carroll, Cass, and Tipton. In 1844, Tipton County was created from Hamilton County's territory, and after being fully organized, Tipton was detached from Hamilton's administrative oversight.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries; the 5 that matter most are shown first.

1823
Hamilton County created Hamilton created from the unattached part of Delaware New Purchase (later Adams New Purchase) and from part of Delaware New Purchase attached to Marion.
from Delaware from Adams from Marion
7 April 1823 · Ind. Acts 1822, 7th sess., ch. 52, secs. 1-2/p. 100
1826
Changed Part of Delaware New Purchase (later Adams New Purchase) was attached to Hamilton for administrative and judicial purposes.
Delaware Adams
13 January 1826 · Ind. Acts 1825, 10th sess., ch. 73, secs. 3-4/p. 81
1827
Lost territory Hamilton lost part of Delaware New Purchase (later Adams New Purchase) attachment to Madison.
to Delaware to Adams to Madison
26 January 1827 · Ind. Acts 1826, 11th sess., ch. 91/p. 84
1828
Lost territory Hamilton lost part of Adams New Purchase attachment to creation of Carroll; part of Adams New Purchase was detached from Hamilton and attached to Carroll for administrative and judicial purposes.
to Adams to Carroll
1 April 1828 · Ind. Acts 1827, 12th sess., ch. 16/p. 21 and ch. 10, secs. 3, 6/p. 14
1844
Lost territory Hamilton lost Adams New Purchase attachment to creation of Tipton; Tipton not fully organized, part attached to Hamilton for administrative and judicial purposes.
to Adams to Tipton
15 January 1844 · Ind. Acts 1843, 28th sess., gen., ch. 3, secs. 1-2, 6/pp. 10-11

Show all 10 changes (5 more)

1823
Hamilton County created Hamilton created from the unattached part of Delaware New Purchase (later Adams New Purchase) and from part of Delaware New Purchase attached to Marion.
from Delaware from Adams from Marion
7 April 1823 · Ind. Acts 1822, 7th sess., ch. 52, secs. 1-2/p. 100
1826
Changed Part of Delaware New Purchase (later Adams New Purchase) was attached to Hamilton for administrative and judicial purposes.
Delaware Adams
13 January 1826 · Ind. Acts 1825, 10th sess., ch. 73, secs. 3-4/p. 81
1827
Lost territory Hamilton lost part of Delaware New Purchase (later Adams New Purchase) attachment to Madison.
to Delaware to Adams to Madison
26 January 1827 · Ind. Acts 1826, 11th sess., ch. 91/p. 84
1828
Changed Part of Adams New Purchase was detached from Hamilton and attached to Delaware, Hendricks, and Tippecanoe for administrative and judicial purposes.
Adams Delaware Hendricks Tippecanoe
24 January 1828 · Ind. Acts 1827, 12th sess., ch. 10/p. 13
1828
Lost territory Hamilton lost part of Adams New Purchase attachment to creation of Carroll; part of Adams New Purchase was detached from Hamilton and attached to Carroll for administrative and judicial purposes.
to Adams to Carroll
1 April 1828 · Ind. Acts 1827, 12th sess., ch. 16/p. 21 and ch. 10, secs. 3, 6/p. 14
1829
Changed Part of Adams New Purchase was detached from Hamilton and attached to Cass for administrative and judicial purposes.
Adams Cass
14 April 1829 · Ind. Acts 1828, 13th sess., ch. 19/p. 26 and ch. 20/p. 28
1830
Changed Part of Adams New Purchase was detached from Hamilton and remained unattached.
Adams
29 January 1830 · Ind. Acts 1829, 14th sess., ch. 13/p. 22
1839
Changed Part of Adams New Purchase (Great Miami Reservation) was attached to Hamilton for administrative and judicial purposes.
Adams
16 February 1839 · Ind. Acts 1838, 23d sess., gen., ch. 63/p. 75
1844
Lost territory Hamilton lost Adams New Purchase attachment to creation of Tipton; Tipton not fully organized, part attached to Hamilton for administrative and judicial purposes.
to Adams to Tipton
15 January 1844 · Ind. Acts 1843, 28th sess., gen., ch. 3, secs. 1-2, 6/pp. 10-11
1844
Changed Tipton fully organized, detached from Hamilton.
Tipton
1 May 1844 · Ind. Acts 1843, 28th sess., gen., ch. 3, sec. 6/p. 11

Land and parcels

What the maps cover in Hamilton

Who publishes each layer, how good it is, and when we last checked.

Parcels Good enough

Lot lines and tax-map numbers for 150,707 parcels from Indiana Geographic Information Office (IndianaMap). Drawn for tax purposes: usually within a few feet of a survey, but not a survey.
edited 6 October 2026 · checked 15 October 2026
Address points Official

One point per address, 177,926 in all from Indiana Geographic Information Office (IGIO).
edited 8 March 2026 · checked 13 October 2026
Buildings Reference

Roof outlines traced from aerial imagery from FEMA Response Geospatial Office with Oak Ridge National Laboratory (ORNL). Good for seeing what is on a lot; not accurate enough to set a fence from.
checked 18 October 2026

Official: from the office that keeps the record
Good enough: a reliable statewide or national copy
Fallback: a guide only; check the official record
Missing: nothing public found yet

People and land

Hamilton by the Census

Population

347,467 2020 Census count

Housing units

135,064 2020 Census count

Land area

394 square miles

Water area

8.1 square miles

People per sq mi

881 population ÷ land area

Source: US Census Bureau, 2020 Census; US Census Bureau, 2020 Gazetteer Files. Not endorsed or certified by the Census Bureau.

Rules and offices

Who to ask before you build, dig or sell

Official county pages only. We link to them; we do not copy them, because they change.

Inside a city or town, permits usually come from that city rather than the county.

Records

Assessor and property records
Tax Calculation
from hamiltoncounty.in.gov · checked 13 October 2026
Clerk of court: deeds and plats
Circuit Court - Judge Andrew R. Bloch
from hamiltoncounty.in.gov · checked 13 October 2026

Permits

Health department: septic and wellfrom hamiltoncounty.in.gov · checked 13 October 2026
Permits and Applicationsfrom hamiltoncounty.in.gov
Permitsfrom hamiltoncounty.in.gov
Well Permitsfrom hamiltoncounty.in.gov
Septic Permitsfrom hamiltoncounty.in.gov

Zoning and code

Planning and zoningfrom hamiltoncounty.in.gov · checked 13 October 2026
HCAA Ordinance 02-11-26-2 (PDF)from hamiltoncounty.in.gov
HCAA Ordinance 02-11-26-01 (PDF)from hamiltoncounty.in.gov
Board of Zoning Appealsfrom hamiltoncounty.in.gov
Board of Zoning Appeals Meeting Datesfrom hamiltoncounty.in.gov

GIS and maps

County GIS and mapsfrom hamiltoncounty.in.gov · checked 13 October 2026

County government

County government
The official website of Hamilton County.
hamiltoncounty.in.gov

See your own lot on these maps

Open Hamilton County on Parcel Chart's free map and click your parcel. Save it with a free account; the full record of your place (site map, projects, documents) is Pro, in early access.

Open the free map no sign-in Pro early access

Questions

Common questions about Hamilton County

When was Hamilton County founded?: Hamilton County was founded in 1823, formed from Delaware County, Adams County and Marion County, and named after Alexander Hamilton.
What is the county seat of Hamilton County?: The county seat of Hamilton County is Noblesville.
Is there an online parcel map for Hamilton County?: Yes. Indiana Geographic Information Office (IndianaMap) publishes a parcel map of 150,707 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Hamilton County's boundary or name changed?: Hamilton County was created in 1823 from Delaware County, Adams County and Marion County. Since then the Atlas of Historical County Boundaries records 9 later changes, chiefly involving Adams County, Delaware County and Tipton County.
Who issues building permits in Hamilton County?: The county's page on building permits: Permits and Applications. Inside a city or town, ask that city first.
Who issues septic and well permits in Hamilton County?: The county's page on septic systems and wells: Health department: septic and well.
Is my lot in a flood zone?: We do not have flood maps for Hamilton County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

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