Idaho looks sparsely populated at the statewide scale, but the detailed maps show that its residents are concentrated in a small number of distinct urban clusters. The 2024 ACS five-year estimate places the state population at 1,934,262. Ada County alone has 518,935 residents and the state’s highest countywide density at about 493 people per square mile. The Boise-area cluster dominates the southwest, while other concentrations appear around Coeur d’Alene and Post Falls in the north, Idaho Falls in the east, Pocatello in the southeast, and Twin Falls in the south-central part of the state. A separate 2010–2020 Census map also shows why current size and growth rate should not be treated as the same thing: Madison County, not Ada, had the fastest percentage increase.
Table of Contents
Start with the measures that answer different questions
| Measure | Value in the supplied material | What it means |
|---|---|---|
| 2024 state population | 1,934,262 | ACS 2024 five-year estimate |
| Average state density | About 23 people per sq mi | Average across 82,645 sq mi of land |
| Largest county population | Ada — 518,935 | Total residents, not density |
| Highest county density | Ada — about 493 people per sq mi | Residents per unit of land |
| Fastest 2010–2020 growth | Madison — +41.0% | Decennial Census percentage change |
| Largest 2010–2020 decline | Clark — -19.6% | Change over the decade |
A proportional circle on the county-population map represents the number of people living in a county. A darker fill on the county-density map represents more people per square mile. The population-change map uses yet another measure: the percentage difference between the 2010 and 2020 decennial censuses. Those maps also use different time periods from the 2024 ACS maps. Keeping the measures separate is especially important in Idaho because some of its geographically large counties contain relatively few residents, while smaller urban counties hold much larger populations.
The tract map reveals a concentrated southwest rather than uniform settlement
The tract-density legend ranges from 0–50 people per square mile through 50–200, 200–500, 500–1,000, 1,000–2,500, 2,500–5,000, 5,000–10,000, and 10,000 or more. Darker tracts contain more residents per unit of land. The broadest visible concentration is in southwest Idaho around the Boise-area counties, where several adjoining tracts form a much stronger pattern than the large low-density areas that occupy much of the state’s interior.
Other dense clusters are smaller but still easy to identify. The northern panhandle contains a prominent concentration around Coeur d’Alene and Post Falls, with additional clusters near Moscow and Lewiston farther south. Eastern Idaho has a clear patch around Idaho Falls and Ammon, while Pocatello and Chubbuck stand out in the southeast. Twin Falls forms another compact concentration in the south-central region. Large sections of central Idaho remain in the lightest density classes. The map notes that large sparsely populated tracts can include mountains, forests, deserts, or public land; that is useful map-reading context, but the map itself should not be used to assign a single cause to the settlement pattern.
Major census places show how several cities combine around Boise
Boise City is the largest census place in the supplied data at 237,242 residents. Meridian follows at 130,138 and Nampa at 110,319. Idaho Falls has 67,725 residents, Caldwell 66,516, Pocatello 57,635, Coeur d’Alene 56,447, and Twin Falls 54,164. The next group includes Post Falls at 43,391, Rexburg at 40,543, Lewiston at 34,651, Eagle at 32,855, Kuna at 27,158, and Moscow at 26,286.
The spatial pattern matters as much as the ranking. Boise is surrounded by several of the state’s other large places: Meridian, Nampa, Caldwell, Eagle, and Kuna create a close cluster in the southwest. In northern Idaho, Coeur d’Alene, Post Falls, and Hayden sit near one another. Idaho Falls and Ammon form an eastern pair, while Pocatello and Chubbuck form another pair in the southeast. The circles are not density symbols; they compare census-place populations. This map therefore complements the tract map by attaching names and relative population sizes to the urban concentrations that appear as dense patches.
Ada and Canyon dominate county population totals
Ada County has 518,935 residents, giving it by far the largest proportional circle on the county-total map. Canyon County is second at 250,790, followed by Kootenai at 181,996 and Bonneville at 129,523. Twin Falls County has 93,734 residents, Bannock 89,454, Madison 54,618, Bonner 51,049, Bingham 49,664, Nez Perce 42,697, and Latah 41,049. The distribution reinforces the importance of southwest Idaho, while also showing substantial county populations in the northern panhandle and eastern Idaho.
Physical county size should not be confused with population size. Idaho County occupies a very large area on the map but has only 17,432 residents in the supplied 2024 estimate. Custer County has 4,470 and Lemhi County 8,249. Their circles are small despite their geographic extent. A total-population map is therefore useful for answering “how many people live here?” but cannot answer “how closely are they packed together?” without the separate density map.
County density exposes an extreme gap between urban counties and the interior
The county-density legend uses 0–10, 10–50, 50–100, 100–250, 250–500, 500–1,000, 1,000–2,500, and 2,500 or more people per square mile. Ada County is highest at about 493 people per square mile, and Canyon follows at about 427. Kootenai is roughly 147, Madison 116, Bannock 80, Bonneville 69, and Payette 66. Nez Perce is about 50 and Twin Falls about 49. These figures show that the largest urban counties are not only populous; several are also much more densely settled than the statewide average.
The state summary printed on the map reports 1,934,262 residents, 82,645 square miles of land, and an average density of about 23 people per square mile. That single average hides very large county differences. Clark County is only about 0.48 person per square mile, Custer about 0.91, Camas about 1.05, and Idaho County about 2.06. Ada’s countywide density is therefore hundreds of times higher than the sparsest counties. The more accurate statewide picture is not simply “low density,” but a landscape of broad sparsely populated areas punctuated by a handful of distinctly dense urban counties.
Madison led 2010–2020 growth while Clark lost nearly one-fifth of its population
This map uses decennial Census counts rather than the 2024 ACS estimates. Its classes are below -10%, -10% to -2%, -2% to 2%, 2% to 10%, 10% to 25%, and 25% or more. Madison County increased from 37,536 residents in 2010 to 52,913 in 2020, a gain of about 41.0%, the largest percentage increase in the supplied county data. Ada grew from 392,365 to 494,967, or about 26.1%. Kootenai rose 23.7%, Canyon 22.3%, Valley 19.1%, Bonneville 18.9%, Jefferson 18.2%, and Twin Falls 16.6%.
Several counties moved in the opposite direction. Clark County fell from 982 residents to 790, a decline of about 19.6%. Butte declined 11.0%, Lewis 7.5%, Camas 3.6%, Custer 2.1%, Lincoln 1.6%, and Clearwater about 0.3%. The comparison is a reminder that percentage growth is not the same as current population rank. Ada is the largest county in the 2024 estimate, but Madison recorded the fastest 2010–2020 growth rate. A smaller county can change rapidly in percentage terms without becoming the state’s largest population center.
What becomes clear when the five views are read together
The strongest recurring signal is southwest Idaho. Boise is the state’s largest census place, several other large cities sit nearby, and Ada County ranks first in both total population and county density. Canyon County ranks second in total population and second in density. The tract map shows the same area as the state’s broadest detailed-density cluster. Because city population, county population, county density, and tract density all point to the same part of Idaho, the Boise-area concentration is not an artifact of any single map type.
The rest of the state is more varied than a simple Boise-versus-rural split. Kootenai County has 181,996 residents, density around 147 people per square mile, and 2010–2020 growth of 23.7%, matching the visible Coeur d’Alene–Post Falls cluster. Madison County has only 54,618 residents in the 2024 estimate but posted the state’s fastest decade growth at 41.0%. Bonneville County combines 129,523 residents with density around 69 and growth of 18.9%, supporting the separate eastern concentration around Idaho Falls. These distinctions make the maps most useful when totals, density, urban places, and historical change are compared rather than collapsed into one ranking.
Download and use the Idaho population map set
Choose the tract-density map when you need fine-grained settlement patterns within counties. Use the county-total map to compare the number of residents and the county-density map to compare people per square mile. The major-cities map is best for locating and comparing named census places, while the 2010–2020 change map is the right choice for decade-long growth or decline. Keep the 2024 ACS estimates separate from the 2010–2020 Census comparison so that current population and historical change are not mixed into the same measure.
Idaho population map collection
The ZIP package contains high-resolution JPG versions of the population maps shown above.
FAQ
Which Idaho county has the highest population density?
Ada County is highest in the supplied 2024 ACS five-year data at about 493 people per square mile. Canyon County is next at about 427, followed by Kootenai at about 147.
Which Idaho county has the largest population?
Ada County is the largest at 518,935 residents in the supplied 2024 ACS estimate. Canyon County has 250,790 and Kootenai County 181,996. Total population and population density are separate measures even though Ada ranks first in both here.
Which Idaho county grew fastest from 2010 to 2020?
Madison County had the largest percentage increase at about +41.0%. Ada grew about +26.1%, Kootenai +23.7%, and Canyon +22.3%. Clark County had the largest decline at about -19.6%.
Related Maps
Official data sources
- U.S. Census Bureau — American Community Survey (ACS): source framework for the 2024 five-year population and density estimates.
- U.S. Census Bureau — TIGER/Line Shapefiles: geographic boundaries for counties, census tracts, census places, and related mapping.
- U.S. Census Bureau — Decennial Census: basis for the 2010 and 2020 county population-change comparison.
Green Map creates custom-edited map images using open geographic data sources such as geoBoundaries, Natural Earth, OpenStreetMap, and government open data.
These maps are edited visual materials, not raw data files, and are provided for education, documents, presentations, and graphic reference.
