The map above shows Iowa and South Dakota side by side at exactly the same scale, using equal-area projections, so their true relative sizes are preserved.
Iowa vs South Dakota Geography
Land area: Iowa has a land area of 55,854 square miles (144,660 km²), while South Dakota has 75,808 square miles (196,342 km²). South Dakota's land area is 1.4 times (36%) larger than Iowa's.
Total area: Iowa: 56,273 square miles (145,746 km²) vs South Dakota: 77,116 square miles (199,729 km²), including inland and coastal water. South Dakota's total area is 1.4 times (37%) larger than Iowa's.
Length: Iowa is 216 miles (347 km) long from north to south; South Dakota is 443 miles (712 km). South Dakota's north-south length is 2.1 times (105%) longer than Iowa's.
Width: Iowa spans 335 miles (539 km) east to west; South Dakota spans 371 miles (597 km). South Dakota's east-west width is 1.1 times (11%) wider than Iowa's.
Highest point: Iowa's highest point is Hawkeye Point at 1,669 feet (509 m); South Dakota's is Black Elk Peak at 7,198 feet (2,194 m). Black Elk Peak is 5,529 feet higher than Hawkeye Point.
Lowest point: Iowa's lowest point is Mississippi River at 480 feet; South Dakota's is Big Stone Lake at 966 feet. Iowa's lowest point is 486 feet lower.
Iowa vs South Dakota Population and History
Population: Iowa has a population of 3,241,488 (2024), while South Dakota has 924,669 (2024). Iowa's population is 3.5 times (251%) larger than South Dakota's.
Population density: Iowa: 58.0 people per square mile vs South Dakota: 12.2. Iowa's population density is 4.8 times (375%) higher than South Dakota's.
Biggest city: Iowa's biggest city is Des Moines with 213,096 people; South Dakota's is Sioux Falls with 209,289. Des Moines and Sioux Falls have about the same population.
Largest metro area: Iowa's largest metropolitan area is Omaha, NE-IA metro area (1,001,010 people) vs South Dakota's Sioux Falls, SD-MN metro area (308,266). Omaha, NE-IA metro area's population is 3.2 times (225%) larger than Sioux Falls, SD-MN metro area's.
History: Iowa: Admitted to the Union on December 28, 1846, as the 29th state. South Dakota: Admitted to the Union on November 2, 1889, as the 40th state. In its current form, Iowa is the older of the two by 43 years.
Iowa vs South Dakota Economy
GDP: Iowa's GDP is $265.8 billion (2024) vs South Dakota's $76.8 billion. Iowa's economic output is 3.5 times (246%) larger than South Dakota's.
GDP per capita: Iowa: $81,998 per person vs South Dakota: $83,052. Iowa and South Dakota have about the same GDP per capita.
Average income: Iowa: $65,225 vs South Dakota: $75,699 average income per person (per capita personal income). South Dakota's average income is 1.2 times (16%) higher than Iowa's.
Iowa vs South Dakota Counties
Number of counties: Iowa has 99 counties, while South Dakota has 66. Iowa's county count is 1.5 times (50%) higher than South Dakota's.
Biggest county by area: Iowa's largest county is Kossuth County at 973 square miles; South Dakota's is Meade County at 3,471 square miles. Meade County's land area is 3.6 times (257%) larger than Kossuth County's.
Smallest county by area: Iowa: Dickinson County (381 sq mi) vs South Dakota: Clay County (412 sq mi). Clay County's land area is 1.1 times (8%) larger than Dickinson County's.
Most populous county: Iowa: Polk County (516,185 people) vs South Dakota: Minnehaha County (208,639 people). Polk County's population is 2.5 times (147%) larger than Minnehaha County's.
Least populous county: Iowa: Adams County (3,606 people) vs South Dakota: Jones County (874 people). Adams County's population is 4.1 times (313%) larger than Jones County's.
Richest county: Iowa: Mitchell County ($98,211 per capita income) vs South Dakota: Union County ($146,712). Union County's income is 1.5 times (49%) richer than Mitchell County's.
Poorest county: Iowa: Decatur County ($46,134 per capita income) vs South Dakota: Ziebach County ($32,778). Decatur County's income is 1.4 times (41%) richer than Ziebach County's.
Iowa vs South Dakota Taxes
State income tax: Iowa has a top income tax rate of 3.8%, while South Dakota has no state income tax. Iowa's top rate is 3.8 percentage points higher.
Property tax: Iowa: 1.29% effective rate vs South Dakota: 1.02% of home value per year. Iowa's rate is 0.27 percentage points higher.
Sales tax: Iowa: 6.94% combined state and average local rate vs South Dakota: 6.11%. Iowa's combined rate is 0.83 percentage points higher.
Official Websites
Iowa official website · South Dakota official website
More Size Comparisons
All Iowa size comparisons · All South Dakota 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.