Madison County, Idaho

Madison County is a county in Idaho, United States, about 30 miles north of Idaho Falls in the
state’s eastern arm. It had a population of 52,913 at the 2020 census, an estimated 54,618 by
2024, and covers 473 square miles (1,230 km2) centred near 43°47′N 111°40′W.

Rexburg is the county seat and by far the largest city; its postal code is 83440. The county
holds 2 incorporated cities and 4 unincorporated communities, and it runs on Mountain Time. Its
FIPS code is 16065.

Towns & Villages in Madison County

Madison County has 6 named places on record: 2 incorporated cities and 4 unincorporated
communities with no local government of their own. CDP stands for census designated place;
Unincorp. covers crossroads and rural communities with no formal boundary. Madison is the
third-smallest county in Idaho by land area, which keeps the list of named places short.

Rexburg holds three-quarters of the county’s population on its own; the four unincorporated
communities are small farm crossroads with no post office of their own and no reliable population
count. Thornton sits about 7 miles south of Rexburg; Hibbard lies northwest of the city near the
Fremont County line, close to where the Teton River crosses into the county.

ZIP Codes

• 83440 — Rexburg (the county’s main ZIP, also serves BYU-Idaho campus addresses)
• 83441 — Rexburg (secondary city ZIP)
• 83460 — Rexburg (BYU-Idaho and PO box ZIP)
• 83448 — Sugar City

Archer, Burton, Hibbard and Thornton have no ZIP code of their own; mail there is delivered
under the Rexburg or Sugar City code, depending on which is closer.

Geography

Madison County sits in the upper Snake River Plain in eastern Idaho, a flat to gently rolling
volcanic bench built up from ancient lava flows and windblown loess soil. Of its 473 square miles,
469 are land and 4.0 are water, about 0.8 percent — the Teton River crosses the county from
northeast to southwest, and the Henry’s Fork of the Snake River forms part of the western
edge. Elevation in Rexburg is 4,862 feet.

Fremont County lies to the north, Teton County, Idaho, to the east, Bonneville County to the
south, and Jefferson County to the west. Fremont County, Bonneville County and Jefferson County all have posts
on this site; Teton County, Idaho, does not.

Demographics

Madison County had a population of 52,913 at the 2020 census, and the latest estimate puts the
county near 54,618 residents in 2024. Rexburg and Sugar City together hold nearly all of that
total, with Rexburg alone accounting for 39,409 residents. Median household income runs about
$60,160, well below Idaho’s statewide figure of $74,942 (2023 ACS) — a gap driven by
the large share of BYU-Idaho students counted as county residents with little or no income.
Population density works out to roughly 113 people per square mile of land.

Economy & Local Life

Educational services employs the most workers in the county, about 5,982 people, reflecting
Brigham Young University–Idaho’s size relative to the county’s population. Health
care and social assistance follows at 3,880 workers, and accommodation and food services at
3,871. BYU-Idaho, a private university run by The Church of Jesus Christ of Latter-day Saints,
dominates Rexburg’s economy and enrolls tens of thousands of students, most living in and
around the city. Madison Memorial Healthcare System, based in Rexburg, employs more than 800
people and serves a six-county region of eastern Idaho. The volcanic soils around Rexburg and
Sugar City support commercial potato and barley farming, a legacy of the area’s sugar-beet
processing history. About 95 percent of county residents belong to the LDS Church, which shapes
much of local civic and social life, including a near-total absence of alcohol sales.

History

The Idaho legislature created Madison County on 18 February 1913, naming it for President
James Madison. LDS Church members settled the area beginning in the 1880s, and Rexburg grew
around what became Ricks College — now BYU-Idaho — founded as an academy in 1888.
Sugar City took its name from a sugar-beet processing factory built there in 1903–1904;
workers who first lived in temporary shacks nicknamed the settlement “Rag Town.”

On 5 June 1976, the newly built Teton Dam upstream in Fremont County failed, releasing more
than two million cubic feet per second of water down the Teton River. The flood killed 11 people,
caused roughly $2 billion in damage, and left about 80 percent of Rexburg’s buildings
damaged; the federal government paid out more than $300 million in claims. The dam was never
rebuilt, and a museum in the basement of the restored Rexburg Tabernacle now documents the
disaster.

Getting There

State Highway 33 runs through Rexburg and Sugar City; U.S. Route 20 clips the county’s
western edge on its way north toward Yellowstone National Park. No interstate crosses Madison
County.

• Idaho Falls — about 30 miles south
• St. Anthony — about 10 miles north
• Driggs — about 30 miles east
• Idaho National Laboratory (Idaho Falls area) — about 30 miles southwest

Idaho Falls Regional Airport, roughly 30 miles south of Rexburg, is the nearest commercial
airport with scheduled service. Rexburg has no Amtrak station; the nearest passenger rail access
is well outside the region, and most long-distance travel runs through Idaho Falls or Salt Lake
City.

Frequently Asked Questions

Where is Madison County, Idaho located?
It sits in eastern Idaho’s Snake River Plain, about 30 miles north of Idaho Falls, bordered
by Fremont, Teton, Bonneville and Jefferson counties.

What is the population of Madison County?
52,913 at the 2020 census, with a 2024 estimate near 54,618.

How big is Madison County?
473 square miles (1,230 km2), of which 469 square miles are land — the third-smallest
county in Idaho by area.

What is the county seat of Madison County?
Rexburg is the county seat and largest city, and hosts Brigham Young University–Idaho.

How many towns are in Madison County?
Two incorporated cities, Rexburg and Sugar City, plus four unincorporated communities: Archer,
Burton, Hibbard and Thornton.

What ZIP codes does Madison County use?
83440, 83441 and 83460 for Rexburg, and 83448 for Sugar City.

What is Madison County known for?
Brigham Young University–Idaho, its overwhelmingly LDS population, and the 1976 Teton Dam
flood that devastated Rexburg and Sugar City.

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