The map above shows Idaho and Washington side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Idaho vs Washington Geography
Land area
- Idaho has a land area of 82,645 square miles (214,051 km²), while Washington has 66,455 square miles (172,119 km²).
- Idaho's land area is 1.2 times (24%) larger than Washington's.
Total area
- Idaho: 83,569 square miles (216,441 km²) vs Washington: 71,301 square miles (184,668 km²), including inland and coastal water.
- Idaho's total area is 1.2 times (17%) larger than Washington's.
Length
- Idaho is 483 miles (778 km) long from north to south; Washington is 238 miles (383 km).
- Idaho's north-south length is 2.0 times (103%) longer than Washington's.
Width
- Idaho spans 352 miles (566 km) east to west; Washington spans 399 miles (641 km).
- Washington's east-west width is 1.1 times (13%) wider than Idaho's.
Highest point
- Idaho's highest point is Borah Peak at 12,631 feet (3,850 m); Washington's is Mount Rainier at 14,409 feet (4,392 m).
- Mount Rainier is 1,778 feet higher than Borah Peak.
Lowest point
- Idaho's lowest point is Snake River at 718 feet; Washington's is Pacific Ocean at 0 feet.
- Washington's lowest point is 718 feet lower.
Idaho vs Washington Population and History
Population
- Idaho has a population of 2,001,619 (2024), while Washington has 7,958,180 (2024).
- Washington's population is 4.0 times (298%) larger than Idaho's.
Population density
- Idaho: 24.2 people per square mile vs Washington: 119.8.
- Washington's population density is 5.0 times (395%) higher than Idaho's.
Biggest city
- Idaho's biggest city is Boise with 237,963 people; Washington's is Seattle with 780,995.
- Seattle's population is 3.3 times (228%) larger than Boise's.
Largest metro area
- Idaho's largest metropolitan area is Boise City, ID metro area (845,877 people) vs Washington's Seattle-Tacoma-Bellevue, WA metro area (4,145,494).
- Seattle-Tacoma-Bellevue, WA metro area's population is 4.9 times (390%) larger than Boise City, ID metro area's.
History
- Idaho: Admitted to the Union on July 3, 1890, as the 43rd state.
- Washington: Admitted to the Union on November 11, 1889, as the 42nd state.
- In its current form, Washington is the older of the two by 1 years.
Idaho vs Washington Economy
GDP
- Idaho's GDP is $129.0 billion (2024) vs Washington's $856.0 billion.
- Washington's economic output is 6.6 times (564%) larger than Idaho's.
GDP per capita
- Idaho: $64,457 per person vs Washington: $107,564.
- Washington's GDP per capita is 1.7 times (67%) higher than Idaho's.
Average income
- Idaho: $62,323 vs Washington: $85,187 average income per person (per capita personal income).
- Washington's average income is 1.4 times (37%) higher than Idaho's.
Idaho vs Washington Counties
Number of counties
- Idaho has 44 counties, while Washington has 39.
- Idaho's county count is 1.1 times (13%) higher than Washington's.
Biggest county by area
- Idaho's largest county is Idaho County at 8,478 square miles; Washington's is Okanogan County at 5,266 square miles.
- Idaho County's land area is 1.6 times (61%) larger than Okanogan County's.
Smallest county by area
- Idaho: Payette County (407 sq mi) vs Washington: San Juan County (174 sq mi).
- Payette County's land area is 2.3 times (134%) larger than San Juan County's.
Most populous county
- Idaho: Ada County (535,799 people) vs Washington: King County (2,340,211 people).
- King County's population is 4.4 times (337%) larger than Ada County's.
Least populous county
- Idaho: Clark County (794 people) vs Washington: Garfield County (2,404 people).
- Garfield County's population is 3.0 times (203%) larger than Clark County's.
Richest county
- Idaho: Blaine County ($202,612 per capita income) vs Washington: King County ($128,684).
- Blaine County's income is 1.6 times (57%) richer than King County's.
Poorest county
- Idaho: Madison County ($29,485 per capita income) vs Washington: Ferry County ($50,456).
- Ferry County's income is 1.7 times (71%) richer than Madison County's.
Idaho vs Washington Taxes
State income tax
- Idaho has a top income tax rate of 5.3%, while Washington has a 9% tax on capital gains only.
Property tax
- Idaho: 0.43% effective rate vs Washington: 0.79% of home value per year.
- Washington's rate is 0.36 percentage points higher.
Sales tax
- Idaho: 6.03% combined state and average local rate vs Washington: 9.57%.
- Washington's combined rate is 3.54 percentage points higher.
Official Websites
Idaho official website · Washington official website
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More Size Comparisons
All Idaho size comparisons · All Washington size comparisons
Area, elevation and boundary figures come from official national statistics and US Census Bureau and Natural Earth boundary data; US state population, economic, county and tax figures come from the US Census Bureau, the Bureau of Economic Analysis and the Tax Foundation. Figures are rounded and for general reference.