Illinois's Capital Reaches Only 19.1% of the State — and Chicago Is 180 Miles From the Capitol

By SimpleMapLab·Published 13 May 2026·Rank #46 of 50 states·↑ All 50 states

Only 19.1% of Illinois’s population lives within 100 miles of Springfield. The state’s largest population centre — Chicago — sits 180 miles from the capital, far outside the 100-mile circle. Illinois ranks #46 of 50 states for capital centrality, meaning 4 states have a less-misplaced capital.

A 100-mile geodesic radius around the Springfield, IL state capitol overlaid on Illinois. 19.1% of Illinois's population lives inside the dashed ring.

19.1%

of Illinois’s population within 100 miles of Springfield

2.42 M

residents inside the radius (of 12.69 M statewide)

125 mi

from Springfield to Illinois’s population centroid

#46

of 50 states ranked by capital-to-population centrality

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

Why this happened

Springfield became Illinois' capital in 1839, partly through Abraham Lincoln's lobbying. At the time it was a reasonable midpoint of the state's population. Chicago — then a town of 4,000 — was the size of a railway suburb. Today Chicago metro holds 9.5 million people, while Springfield holds 113,000. The 100-mile radius around Springfield reaches 19.1% of Illinois' population; Chicago sits 180 miles north, beyond the circle.

Illinois is the cleanest example of "the city won, but the capital didn't move." Every Illinois governor since Otto Kerner has had to commute between Springfield (the official seat) and Chicago (the place where state business actually gets done). The Thompson Center in downtown Chicago houses a second governor's office for this reason.

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 Springfield. Cities are listed by total population captured by ZIP centroids in the dataset.

#	City	Population in radius
1	Springfield	137,282
2	Peoria	126,889
3	Champaign	96,852
4	Belleville	93,551
5	Bloomington	85,628

The largest city outside the radius

Illinois’s most-populous city outside the 100-mile circle is Chicago, sitting 180 miles from Springfield. The aggregated population of Chicago’s ZIP codes alone — 2,694,535 residents — illustrates the gap between Illinois’s political seat and its population centre.

How Illinois compares

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

#45 Texas

Austin · 21.3% pop. captured

#47 New York

Albany · 14.7% pop. captured

#44 Nevada

Carson City · 21.8% pop. captured

#48 South Dakota

Pierre · 10.8% pop. captured

#43 Wyoming

Cheyenne · 27.9% pop. captured

Draw it yourself

Open the 100-mile circle around Springfield →

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 Springfield’s reach with that of Springfield, or add a second circle for a side-by-side comparison.

Methodology (brief)

We took the lat/lng of the Illinois state capitol building (39.7817°, -89.6501°) and drew a 100-mile geodesic radius. For every ZIP code in Illinois, we tested whether the ZIP centroid falls inside; if so, its population counts. We then divide by Illinois’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 Springfield: How Much of Illinois Is Inside? Part of the State Capital Radius study. Retrieved from https://www.simplemaplab.com/studies/state-capital-radius/illinois. Licensed under CC-BY 4.0.