Des Moines's 100-Mile Reach Captures 49.8% of Iowa; 50.2% of the State Lives Outside

By SimpleMapLab·Published 13 May 2026·Rank #36 of 50 states·↑ All 50 states

49.8% of Iowa’s population — about 1.60 M of 3.21 M residents — lives within 100 miles of Des Moines. The other 50.2% — including Cedar Rapids — sits beyond the circle.

A 100-mile geodesic radius around the Des Moines, IA state capitol overlaid on Iowa. 49.8% of Iowa's population lives inside the dashed ring.

49.8%

of Iowa’s population within 100 miles of Des Moines

1.60 M

residents inside the radius (of 3.21 M statewide)

38 mi

from Des Moines to Iowa’s population centroid

#36

of 50 states ranked by capital-to-population centrality

Open this radius in the map → /tools/map-radius-tool · Des Moines, IA · 100 mi
The link opens the SimpleMapLab Map Radius Tool with the 100-mile circle already drawn around the Des Moines capitol. Change the radius to 50, 250, or any value to compare different framings.

Why this happened

Iowa is a "split" state by this measure: roughly half its residents live within an hour and a half of the capital, and roughly half live beyond. Des Moines's 100-mile reach captures Des Moines (~220K) and the surrounding counties, but stops well short of Cedar Rapids, which sits 105 miles away. The capital-to-population-centroid distance is 38 miles — a clear signal that political and demographic weight no longer share a single point on the map.

The biggest cities inside the 100-mile radius

The top 5 most-populous places (by aggregated ZIP code population) sitting inside the 100-mile circle around Des Moines. Cities are listed by total population captured by ZIP centroids in the dataset.

#	City	Population in radius
1	Des Moines	220,322
2	Ankeny	76,589
3	Ames	72,881
4	West Des Moines	71,011
5	Waterloo	69,066

The largest city outside the radius

Iowa’s most-populous city outside the 100-mile circle is Cedar Rapids, sitting 105 miles from Des Moines. The aggregated population of Cedar Rapids’s ZIP codes alone — 145,496 residents — illustrates the gap between Iowa’s political seat and its population centre.

How Iowa compares

The states ranked closest to Iowa on this metric. Click any to compare the radius breakdown directly.

#35 Arkansas

Little Rock · 51.4% pop. captured

#37 Mississippi

Jackson · 49.4% pop. captured

#34 Idaho

Boise · 51.8% pop. captured

#38 Montana

Helena · 45.1% pop. captured

#33 Alabama

Montgomery · 52.5% pop. captured

Draw it yourself

Open the 100-mile circle around Des Moines →

The Map Radius Tool lets you change the radius (try 50 mi for an urban-suburban question or 250 mi for “a day’s drive”), drag the centre to compare Des Moines’s reach with that of Des Moines, or add a second circle for a side-by-side comparison.

Methodology (brief)

We took the lat/lng of the Iowa state capitol building (41.5868°, -93.6250°) and drew a 100-mile geodesic radius. For every ZIP code in Iowa, we tested whether the ZIP centroid falls inside; if so, its population counts. We then divide by Iowa’s total population to produce the percentage. The full methodology for all 50 states is on the hub page.

Suggested citation: SimpleMapLab (2026). 100 Miles Around Des Moines: How Much of Iowa Is Inside? Part of the State Capital Radius study. Retrieved from https://www.simplemaplab.com/studies/state-capital-radius/iowa. Licensed under CC-BY 4.0.