Canyon County area

Population and density of Canyon County

The Census Bureau estimates that 275,123 people lived in Canyon County on July 1, 2025. That ranks #271 of 3,222 county equivalents nationally and #2 of 44 in Idaho. Since the April 1, 2020 estimates base of 231,107, the population has grown by 44,016 (+19%), compared with +10.4% for Idaho as a whole.

With 587 square miles of land, that is 469 people per square mile (181 per km²), placing Canyon County #358 nationally for density and #2 in Idaho. The median county equivalent has 47 people per square mile; the Idaho median is 10. Put another way, there are about 1.4 acres of land per resident.

U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.

Cities and towns in Canyon County

9 incorporated places lie at least partly in Canyon County. Together they are home to 215,643 people (78.4%); the other 59,480 (21.6%) live outside any incorporated place, in unincorporated communities and rural areas.

The largest is Nampa city, with 120,384 residents in the county. The county seat, Caldwell city, has 76,629 residents. Among places with at least 1,000 residents in 2020, Middleton city grew fastest since then (+33.3%).

Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Canyon County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.

Metropolitan area

Canyon County is an outlying county of the Boise City, ID Metropolitan Statistical Area. Its 5 county equivalents have 864,243 residents on 11,766.6 square miles of land; Canyon County accounts for 5% of the land and 31.8% of the residents. By combined land it ranks #6 of 393 metropolitan areas, and #75 by population. It belongs to the Boise City-Mountain Home-Ontario, ID-OR Combined Statistical Area.

ZIP codes

13 ZIP Code Tabulation Areas have land in Canyon County; 10 of them have most of their land inside the county, and the others mainly cover neighboring areas.

83605836078362683634836418364483651836568366083669836768368683687

ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.

Counties bordering Canyon County

Canyon County shares a land border with 5 county equivalents, including 1 in Oregon. It has more land than 2 of them. The largest neighbor is Malheur County (9,887.7 mi²) and the smallest is Payette County (406.9 mi²). Together with its neighbors, Canyon County forms a block of 20,161.9 mi² of land, of which it holds 2.9%.

How big is Canyon County compared with U.S. states?

Canyon County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.8 times as much. Idaho’s county land could hold about 141 areas the size of Canyon County.

Another way to picture it: the same land area would fill a square about 24.2 miles (39 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.

State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.

What stands out about Canyon County?

Canyon County has more land than 1,550 of the other 3,221 county equivalents in the dataset.

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Canyon County at #1,729 nationally by total area, 57 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.

Its water share is 2.8%, compared with a national county-equivalent median of 1.2% — 1.6 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Canyon County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.