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County · code 55055

Jefferson CountyWisconsin

Jefferson County is a county in Wisconsin, with its seat in Jefferson. It was created on December 7, 1836, from Milwaukee County and named after Thomas Jefferson.

  • Founded1836
  • County seatJefferson
  • Named forThomas Jefferson
  • Land area556 sq mi + 26 sq mi water
  • Population84,900 2020 Census
  • Parcels mapped44,985 checked 16 October 2026
Open the free map Click any parcel in Jefferson County: acreage, parcel id, address and who publishes the map. No sign-in.

Updated

RockWaukeshaDane Jefferson Census outline · seat marked

Where it is

Jefferson on the map of Wisconsin

Wisconsin has 72 counties and county equivalents, each with its own records office. Shapes with a page are links.

Adams CountyAshland CountyBarron CountyBayfield CountyBrown CountyBuffalo CountyBurnett CountyCalumet CountyChippewa CountyClark CountyColumbia CountyCrawford CountyDane CountyDodge CountyDoor CountyDouglas CountyDunn CountyEau Claire CountyFlorence CountyFond du Lac CountyForest CountyGrant CountyGreen CountyGreen Lake CountyIowa CountyIron CountyJackson CountyJuneau CountyKenosha CountyKewaunee CountyLa Crosse CountyLafayette CountyLanglade CountyLincoln CountyManitowoc CountyMarathon CountyMarinette CountyMarquette CountyMenominee CountyMilwaukee CountyMonroe CountyOconto CountyOneida CountyOutagamie CountyOzaukee CountyPepin CountyPierce CountyPolk CountyPortage CountyPrice CountyRacine CountyRichland CountyRock CountyRusk CountySt. Croix CountySauk CountySawyer CountyShawano CountySheboygan CountyTaylor CountyTrempealeau CountyVernon CountyVilas CountyWalworth CountyWashburn CountyWashington CountyWaukesha CountyWaupaca CountyWaushara CountyWinnebago CountyWood CountyJefferson County Jefferson
Counties of Wisconsin · Jefferson highlighted

History

Formed in 1836 from Milwaukee County

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

Jefferson County was created by Wisconsin Territory on December 7, 1836, from Milwaukee County, but was not initially fully organized and remained attached to Milwaukee for judicial purposes. On February 28, 1839, Jefferson County was fully organized and detached from Milwaukee. On May 29, 1848, Jefferson County became a county in the state of Wisconsin.

Boundary changes from the Newberry Library, Atlas of Historical County Boundaries.

  1. 1836
    Jefferson County created Jefferson created by Wisconsin Territory from Milwaukee; Jefferson not fully organized, attached to Milwaukee "for judicial purposes."
    from Milwaukee
    · Wis. Terr. Laws 1836, no. 28, secs. 3, 14/pp. 93-94
  2. 1839
    Changed Jefferson fully organized, detached from Milwaukee.
    Milwaukee
    · Wis. Terr. Laws 1838-1839, loc. acts, no. 35, sec. 1/p. 63
  3. 1840
    Changed Dodge detached from Milwaukee, attached to Jefferson "for judicial purposes."
    DodgeMilwaukee
    · Wis. Terr. Laws 1839-1840, no. 42, secs. 1, 5-6/pp. 50-51
  4. 1844
    Changed Dodge fully organized, detached from Jefferson.
    Dodge
    · Wis. Terr. Laws 1843-1844, pp. 11-13
  5. 1846
    Changed Legislature authorized creation of a new, unnamed county from Jefferson and Dodge, dependent on local referendum that failed; county was never created.
    Dodge
    · HRS Wis., Origin, 99; Wis. Terr. Laws 1846, pp. 48-49
  6. 1848
    Became part of Wisconsin Jefferson became a county in the state of Wisconsin. · U.S. Stat., vol. 9, ch. 89 [1846]/pp. 56-58, and ch. 50 [1848]/pp. 233-235; Van Zandt, 128, 130
  7. 1856
    Changed Legislature authorized Jefferson to gain ranges 13-17 in township 9 north from Dodge, dependent upon a local referendum. Referendum was never held (no change).
    Dodge
    · Abram Smith, 17-27; History of Dodge, 360; Swart, 22; Wis. Laws 1856, reg. sess., gen., ch. 27, secs. 1-2/pp. 30-31; Wis. Laws 1858, gen., ch. 90, secs. 1-2/p. 104

Land and parcels

What the maps cover in Jefferson

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

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

Jefferson by the Census

Population
84,900 2020 Census count
Housing units
36,376 2020 Census count
Land area
556 square miles
Water area
26 square miles
People per sq mi
153 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

Permits

Zoning and code

County government

See your own lot on these maps

Open Jefferson 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.

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Questions

Common questions about Jefferson County

When was Jefferson County founded?
Jefferson County was founded in 1836, formed from Milwaukee County, and named after Thomas Jefferson.
What is the county seat of Jefferson County?
The county seat of Jefferson County is Jefferson.
Is there an online parcel map for Jefferson County?
Yes. Jefferson County publishes a parcel map of 44,985 parcels, rated good enough here. You can click any parcel on it in Parcel Chart's free map, no sign-in needed.
Has Jefferson County's boundary or name changed?
Jefferson County was created in 1836 from Milwaukee County. Since then the Atlas of Historical County Boundaries records 4 later changes, chiefly involving Dodge County and Milwaukee County.
Who issues building permits in Jefferson County?
The county's page on building permits: Building Permit. Inside a city or town, ask that city first.
Who issues septic and well permits in Jefferson County?
The county's page on septic systems and wells: Crisis Line / Mental Health.
Is my lot in a flood zone?
We do not have flood maps for Jefferson County yet. Look up the address on FEMA's Flood Map Service Center, which shows the effective flood map for any lot.

Nearby

Counties next door