Jefferson County is a county in Kansas, United States, on the northern edge of the Topeka metropolitan area, about 15 miles north of Lawrence. It had a population of 18,368 at the 2020 census and covers 557 square miles (1,440 km2), of which 24 square miles is water, centred near 39°13′N 95°21′W.
Oskaloosa is the county seat, and its postal code is 66066. The county has eight incorporated cities, about a dozen unincorporated communities and lake or manufactured-home settlements, and twelve civil townships. Jefferson County is in the Central time zone.
Towns & Villages in Jefferson County
Eight places in Jefferson County are incorporated cities; the rest are unincorporated communities, two of them recognized census-designated places (CDPs). The table below carries over every settlement named in the county’s earlier listing (one duplicate “Williamstown” entry removed) plus Mooney Creek from the current Wikipedia community list.
| Place | Type | Township | Pop. | ZIP |
|---|---|---|---|---|
| Oskaloosa | City · seat | Oskaloosa | 1,110 | 66066 |
| McLouth | City | — | — | 66054 |
| Meriden | City | — | — | 66512 |
| Nortonville | City | — | — | 66060 |
| Ozawkie | City | Ozawkie | — | 66070 |
| Perry | City | — | — | 66073 |
| Valley Falls | City | — | — | 66088 |
| Winchester | City | — | — | 66097 |
| Grantville | CDP | — | — | 66429 |
| Williamstown | CDP | — | — | — |
| Rock Creek | Unincorp. | Rock Creek | — | — |
| Anderson MH Park | Unincorp. | — | — | — |
| Boyle | Unincorp. | — | — | — |
| Buck Creek | Unincorp. | — | — | — |
| Dunavant | Unincorp. | — | — | — |
| Half Mound | Unincorp. | — | — | — |
| Hilldale | Unincorp. | — | — | — |
| Hilldale South | Unincorp. | — | — | — |
| Indian Ridge | Unincorp. | — | — | — |
| Lake Ridge | Unincorp. | — | — | — |
| Lake Shore | Unincorp. | — | — | — |
| Lakeside Village | Unincorp. | — | — | — |
| McConnaugheys MH Park | Unincorp. | — | — | — |
| Medina | Unincorp. | — | — | — |
| Mooney Creek | Unincorp. | — | — | — |
| Newman | Unincorp. | — | — | — |
| Perry Plaza Court MH Park | Unincorp. | — | — | — |
| Thompsonville | Unincorp. | — | — | — |
| West Shore | Unincorp. | — | — | — |
Townships
Jefferson County is divided into twelve civil townships, which double as vote-counting and rural-services districts. Populations are 2020 census figures.
| Township | Pop. (2020) | Main settlements |
|---|---|---|
| Rock Creek | 2,718 | Rock Creek, Lake Ridge, Lake Shore |
| Oskaloosa | 2,142 | Oskaloosa |
| Delaware | 2,034 | Nortonville, McLouth |
| Union | 1,672 | Meriden, Grantville |
| Kentucky | 1,576 | Perry |
| Fairview | 1,510 | Valley Falls |
| Kaw | 1,409 | Williamstown |
| Ozawkie | 1,408 | Ozawkie |
| Jefferson | 1,240 | Winchester |
| Sarcoxie | 958 | Medina |
| Norton | 955 | Half Mound |
| Rural | 804 | Dunavant, Buck Creek |
Township-to-settlement pairings above reflect proximity, not confirmed corporate boundaries for every hamlet; treat the “main settlements” column as indicative.
ZIP Codes
- 66066 — Oskaloosa (county seat)
- 66054 — McLouth
- 66512 — Meriden
- 66060 — Nortonville
- 66070 — Ozawkie
- 66073 — Perry
- 66088 — Valley Falls
- 66097 — Winchester
- 66429 — Grantville
Smaller unincorporated communities and lake or mobile-home settlements use the ZIP code of their nearest post-office town rather than one of their own.
Geography
Jefferson County sits in the Glaciated Region of northeastern Kansas, a landscape of rolling till hills, creek bottoms and the broad Delaware and Kansas river valleys. Perry Lake, formed by a U.S. Army Corps of Engineers dam on the Delaware River, covers much of the county’s water area and its surrounding state park draws most of the county’s recreational traffic; the Kansas River forms part of the southern county line. Of the county’s 557 square miles, 24 square miles is water.
Jefferson County borders Atchison County to the north, Leavenworth County to the east, Douglas County to the south, Shawnee County to the southwest, and Jackson County to the northwest.
Demographics
Jefferson County had 18,368 residents at the 2020 census, giving a density of about 34 people per square mile of land. Oskaloosa and McLouth are its largest incorporated cities, though most residents live in unincorporated areas or one of the lake communities around Perry Lake. Census figures show the county is 91.4% White and 3.1% Hispanic or Latino. Household income in the county tends to run close to the Kansas median of $70,333, reflecting a mix of Topeka-commuter households and farm income.
Economy & Local Life
Agriculture — row crops, cattle and hay ground on the till prairie — remains the traditional base of the county’s economy, alongside gravel and quarry operations along the Kansas and Delaware river valleys. A large share of working residents commute to jobs in Topeka or Lawrence. Perry Lake and Perry State Park support a seasonal tourism and marina economy, drawing boaters, campers and anglers from the Topeka–Kansas City corridor each summer.
History
Jefferson County was organized on August 25, 1855, one of the original counties laid out under the Kansas Territory, and named for President Thomas Jefferson. Its early settlement followed the Kansas and Delaware river valleys, with towns platted at natural river crossings and later along the railroad lines that reached the county in the 1860s–70s. In 1888 Oskaloosa elected Mary D. Lowman as mayor along with an all-women city council, the first all-female municipal government in Kansas. Perry Lake and its dam, completed in the 1960s, reshaped the county’s northeastern townships and remain its defining public-works project.
Getting There
U.S. Route 24 crosses the county’s south-central townships, U.S. Route 59 runs north–south through Oskaloosa, and K-92 links Perry, Ozawkie and Valley Falls. Approximate distances from Oskaloosa:
- Topeka — 20 miles southwest
- Lawrence — 15 miles south
- Leavenworth — 25 miles east
- Kansas City, Mo. — 50 miles east
The nearest commercial airport is Kansas City International Airport (MCI), roughly an hour’s drive east.
Frequently Asked Questions
Where is Jefferson County, Kansas?
It is in northeastern Kansas, on the northern edge of the Topeka metropolitan area, about 15 miles north of Lawrence.
What is the population of Jefferson County?
18,368 at the 2020 census.
How big is Jefferson County?
557 square miles (1,440 km2), of which 24 square miles is water.
What is the county seat of Jefferson County?
Oskaloosa is the county seat.
How many towns are in Jefferson County?
Eight incorporated cities — McLouth, Meriden, Nortonville, Oskaloosa, Ozawkie, Perry, Valley Falls and Winchester — plus around twenty unincorporated communities and lake settlements.
What ZIP codes are in Jefferson County?
Nine ZIP codes serve the county, from 66066 (Oskaloosa) to 66429 (Grantville); see the ZIP Codes section above for the full list.
What is Perry Lake?
A U.S. Army Corps of Engineers reservoir on the Delaware River in the county’s northeast, the centre of its state park and its main recreation draw.
More counties in this state: Towns and villages in Kansas.