Clayton County, Iowa

Clayton County is a county in Iowa, United States, about 45 miles southeast of Dubuque along
the Mississippi River bluffs. It had a population of 17,043 at the 2020 census, an estimated
16,845 by 2024, and covers 792.63 square miles (2,052.90 km2) centred near 42°50′N 91°19′W.

Elkader is the county seat; its postal code is 52043. The county holds 18 incorporated cities
and 23 unincorporated communities across 23 townships, and it runs on Central Time. Its FIPS
code is 19043.

Towns & Villages in Clayton County

Clayton County has 41 named places on record: 18 incorporated cities, including Elkader, and
23 unincorporated communities with no local government of their own. Unincorp. covers crossroads
and rural settlements with no formal boundary; none of the county’s unincorporated places has
been designated a census-tracked CDP.

Two places on this list straddle county lines. Postville’s population figure above is
citywide — most of the city and its downtown sit in Allamakee County, with only its
southern edge, in Grand Meadow Township, reaching into Clayton County. Edgewood runs the
opposite way: Highway 3 through the middle of town marks the Clayton–Delaware county
line, so roughly half its residents are Delaware County residents, not Clayton County ones.
McGregor Heights, despite the shared name, is a separate unincorporated community next to
McGregor rather than a neighborhood inside the city limits.

Townships

Clayton County has 23 civil townships; the 1900 US Census recorded populations for each, but
the Census Bureau has not published township-level counts since townships stopped serving as
independent statistical areas, so current township population figures are not available. Nine
townships name-match a city or unincorporated community they contain; the other 14, listed
above without a settlement, are rural farmland with no platted town of their own.

ZIP Codes

• 52043 — Elkader (the county seat)
• 52052 — Guttenberg (also serves Osterdock, a separate incorporated city with no ZIP
  of its own)
• 52162 — Postville (Clayton County’s southern edge only; most of the ZIP area is in
  Allamakee County)
• 52159 — Monona
• 52076 — Strawberry Point
• 52042 — Edgewood (the Clayton County side; the Delaware County side of town also uses
  this ZIP)
• 52049 — Garnavillo (also serves Clayton, the smaller city of the same-numbered ZIP)
• 52157 — McGregor
• 52158 — Marquette
• 52156 — Luana
• 52047 — Farmersburg
• 52077 — Volga
• 52066 — North Buena Vista
• 52072 — St. Olaf
• 52048 — Garber
• 52044 — Elkport

The county’s 23 unincorporated communities have no ZIP code of their own; mail there is
delivered under the nearest incorporated city’s code, and several, including Froelich and
Turkey River, no longer have an active post office at all.

Geography

Clayton County lies in Iowa’s Driftless Area, a hilly, unglaciated region of deep stream
valleys and Mississippi River bluffs that missed the ice-sheet flattening that leveled most of
the state. Of its 792.63 square miles, 778.46 are land and 14.17 are water, about 1.8 percent
— concentrated in the Mississippi River, which forms the county’s entire eastern border,
and the Turkey and Volga rivers, which cut through the interior on their way to it. Effigy
Mounds National Monument, a National Park Service site preserving Native American burial
mounds, sits on the Mississippi bluffs near Marquette, partly within the county.

Allamakee County lies to the north, Winneshiek County to the northwest, Fayette County to
the west, Buchanan County to the southwest, Delaware County to the south, and Dubuque County to
the southeast; Grant County and Crawford County, both in Wisconsin, lie across the Mississippi
to the east. Allamakee County,
Winneshiek County,
Fayette County,
Buchanan County,
Delaware County,
Dubuque County,
Grant County and
Crawford County all
border Clayton directly.

Demographics

Clayton County had a population of 17,043 at the 2020 census, and the latest Census Bureau
estimate puts the county near 16,845 residents, a slow decline typical of rural northeast Iowa.
Postville and Guttenberg are the two largest communities; together their roughly 4,320 residents
account for about a quarter of the county’s population, though most of Postville’s own total
sits just across the line in Allamakee County. Median household income runs $67,242, somewhat
below Iowa’s statewide figure of $71,433. Population density works out to about 22 people per
square mile of land, low even by rural Iowa standards, reflecting the county’s hilly, hard-to-
farm Driftless terrain.

Economy & Local Life

Manufacturing employs the most workers in the county, about 1,384 people, followed by retail
trade at 987 and construction at 962. Pattison Sand Company, based in Garnavillo, mines St.
Peter Sandstone for industrial silica and limestone aggregate, including proppants used in
hydraulic fracturing. In Postville, Agri Star Meat & Poultry runs a kosher meatpacking plant
on the site of the former Agriprocessors facility, and Norplex-Micarta manufactures composite
laminates, together anchoring the city’s economy. Away from those two employers, the county
runs on row-crop and dairy farming across its uplands and cattle grazing in its steeper river
valleys. The Driftless Area’s cold-water streams, some of the best trout fishing water in Iowa,
and Effigy Mounds National Monument draw recreational visitors through the county each year.

History

Iowa’s territorial legislature organized Clayton County on 21 December 1837, one of the
state’s earliest counties. It was named for John M. Clayton, a United States Senator from
Delaware who later served as US Secretary of State. Elkader, platted in 1846 by Timothy Davis,
John Thompson and Chester Sage, took its name from Emir Abdelkader, the Algerian leader then
resisting French conquest; the city keeps a sister-city relationship with Mascara, Algeria,
his birthplace. Garnavillo served as the county’s first seat before Elkader took over.

Elkport, on the Turkey River, was largely destroyed by a series of floods; after the worst,
in May 2004, most remaining residents accepted a federal buyout and nearly all of the town’s
buildings were demolished by 2006, leaving the city’s population at 29 by the 2020 census.

Getting There

US Route 18 crosses the county through Postville, Elkader and Marquette, and US Route 52
runs along the Mississippi River through Guttenberg and McGregor; no interstate highway
reaches Clayton County. Iowa Highways 3, 13, 56, 76 and 128 connect the county’s smaller
towns.

• Dubuque — about 45 miles southeast
• Decorah — about 30 miles northwest
• Waterloo — about 60 miles southwest
• Prairie du Chien, Wisconsin — about 20 miles east, across the river from Marquette

Dubuque Regional Airport, about 45 miles southeast of Elkader, is the nearest commercial
airport. No Amtrak station operates within Clayton County; the closest, in La Crosse,
Wisconsin, is served by the Empire Builder route, roughly 55 miles northeast.

Frequently Asked Questions

Where is Clayton County located?
It sits in northeastern Iowa’s Driftless Area, along the Mississippi River, about 45 miles
southeast of Dubuque, bordered by Allamakee, Winneshiek, Fayette, Buchanan, Delaware and
Dubuque counties in Iowa and Grant and Crawford counties in Wisconsin.

What is the population of Clayton County?
17,043 at the 2020 census, with a recent estimate near 16,845.

How big is Clayton County?
792.63 square miles (2,052.90 km2), of which 778.46 square miles are land.

What is the county seat of Clayton County?
Elkader, platted in 1846 and named for the Algerian leader Emir Abdelkader.

How many towns and cities are in Clayton County?
Eighteen incorporated cities, led by Postville, Guttenberg and Monona, plus 23 unincorporated
communities with no local government of their own.

What ZIP codes does Clayton County use?
52043 for Elkader, 52052 for Guttenberg and Osterdock, 52162 for the Clayton County edge of
Postville, and separate codes for each of the county’s other incorporated cities, listed above.

What is Clayton County known for?
Effigy Mounds National Monument, the Elkader Keystone Bridge, and Elkport, a town largely
erased by the 2004 Turkey River flood.

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