Bordering states
Idaho vs Washington
Short answer
- ID
- 2,001,619
- WA
- 7,958,180
The two states, county by county
Both maps share one density scale, so the same shade means the same number of people per square mile on either side of the border. Darker counties are denser. Select a county to open its page.
Idaho
Washington
- < 5
- < 13
- < 35
- < 82
- ≥ 82
Residents, 2024
- 01Idaho2,001,619
- 02Washington7,958,180
Land, square miles
- 01Idaho82,645
- 02Washington66,455
People per square mile
- 01Idaho24.2
- 02Washington119.8
Median county household income
- 01Idaho$67,254
- 02Washington$71,374
Side by side
| Measure | Idaho | Washington |
|---|---|---|
| Residents, 2024 | 2,001,619 | 7,958,180 |
| Rank by population | 38th | 13th |
| Land, sq mi | 82,645 | 66,455 |
| People per sq mi | 24.2 | 119.8 |
| County-equivalents | 44 | 39 |
| Median county residents | 15,019 | 69,632 |
| Median county income | $67,254 | $71,374 |
| Most populous county | Ada County | King County |
| Largest county by land | Idaho County | Okanogan County |
| Capital | Boise | Olympia |
| Daylight at capital, June 21 | 15 h 26 min | 15 h 54 min |
| Census division | Mountain | Pacific |
Population and density
Washington has 7,958,180 residents, 4.0 times Idaho's 2,001,619. Idaho ranks 38th and Washington 13th of the 50 states and DC. Washington is the more crowded, with 119.8 people per square mile against 24.2, 4.9 times.
Land area
Idaho has 82,645 square miles of land, 24% more than Washington's 66,455. The largest county-equivalent in Idaho is Idaho County at 8,478 square miles; in Washington it is Okanogan County at 5,266.
Counties
Idaho is divided into 44 county-equivalents and Washington into 39, so an average Idaho county covers 1,878 square miles against 1,704. The typical county in Idaho has 15,019 residents, against 69,632 in Washington. The most populous are Ada County (535,799) and King County (2,340,211).
6 county names appear on both sides of the border: Adams, Clark, Franklin, Jefferson, Lewis, Lincoln. Use the FIPS code, not the name, when joining data across the two states.
Household income
The median county in Washington has a household income of $71,374, 6% above Idaho's $67,254. The highest county incomes are Teton County ($94,895) in Idaho and King County ($120,672) in Washington, from SAIPE 2023.
Capitals and daylight
Boise and Olympia are 401 miles apart in a straight line; from Boise the initial bearing is 308°, NW. On June 21, 2026, Boise gets 15 h 26 min of daylight and Olympia 15 h 54 min; on December 21 the figures are 8 h 56 min and 8 h 30 min. Month by month tables are on the Boise and Olympia daylight pages.
Where they sit
Both are in the West region, but Idaho is in the Mountain division and Washington in the Pacific division. By county internal points, Idaho spans 2 UTM zones and Washington 2.
Questions people ask
Which is bigger, Idaho or Washington?
Idaho, with 82,645 square miles of land against 66,455, 1.24 times as large.
Which has more people, Idaho or Washington?
Washington has 7,958,180 residents, 4.0 times Idaho's 2,001,619.
How far is Boise from Olympia?
401 miles in a straight line, heading NW (308°) from Boise.
Do Idaho and Washington have counties with the same name?
Yes, 6: Adams, Clark, Franklin, Jefferson, Lewis, Lincoln.
Sources and data as of
Data as of: Census Vintage 2024 population estimates, 2024 Gazetteer land area and internal points, SAIPE 2023 median household income.
- 01Census Vintage 2024 county population estimates
- 02Census 2024 Gazetteer, counties
- 03Census SAIPE 2023 state and county estimates
- 04Census Bureau regions and divisions of the United States (last verified 2026-09-30)
How every number is computed: methodology. Spotted a wrong figure? Report an error.