IA · GEOID 19115

Louisa County area

Louisa County, Iowa covers 417.5 square miles: 401.8 square miles of land and 15.7 square miles of water.

Official Census measurements2026 Gazetteer · retrieved September 27, 2026
Land area401.8 mi²
Water area15.7 mi²
Total area417.5 mi²
National land rank#2516

County outline

Generalized outline of Louisa County, Iowa
2025 Census cartographic boundary, fitted to this frame. County maps are not at a common scale. The 2026 area measurements below come from the separate Gazetteer release. Map source and limitations.

Where Louisa County is located

Louisa County highlighted on a map of all U.S. county equivalents. About the maps

Area breakdown

Land accounts for 96.2% of Louisa County’s measured area and water for 3.8%. Its combined area converts to 1,081.4 square kilometers or approximately 267,215 acres.

Green: land · blue: water

MeasurementSquare milesSquare kilometersAcres
Land401.7771,040.598257,137.3
Water15.74740.78510,078.1
Total417.5241,081.382267,215.4

How Louisa County compares

By original Census land area, Louisa County ranks #94 of 99 in Iowa and #2516 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.

Its land area is 0.705 times the Iowa county-equivalent median of 569.6 square miles. It accounts for 0.7% of the combined county land area in the state.

See the complete Iowa ranking · What counts as a county equivalent?

What stands out about Louisa County?

Louisa County has more land than 706 of the other 3,221 county equivalents in the dataset.

Land area compared with the typical county equivalent
Louisa County401.8 mi²
Iowa median569.6 mi²
National median604.5 mi²

A median is the middle county-equivalent measurement, not the average of the largest and smallest. All three bars use the same linear scale. Very small areas may appear as a thin sliver; the labels retain their values.

Does including water change its rank?

Using land plus water places Louisa County at #2,502 nationally by total area, 14 places closer to the top than its land rank. The water assigned to this geography moves it ahead of some county equivalents with more land.

Its water share is 3.8%, compared with a national county-equivalent median of 1.2% — 2.6 percentage points higher. This describes the statistical geography’s land/water mix, not flood exposure or developable land.

Closest positions in the national land ranking

These entries sit immediately beside Louisa County in the national ranking. They can be in different states and are not necessarily geographic neighbors.

Land rankCounty equivalentLand mi²Comparison
#2515Crawford County, Ohio401.8Compare
#2516Louisa County, Iowa401.8This county
#2517Newton County, Indiana401.8Compare

Calculated from the same Census release as the area table. Total-area order uses original ALAND + AWATER; water shares and chart labels use published square miles. Calculation details.

Representative coordinates

The Census internal point is 41.218211, -91.256994. It represents a location inside the geography; it is not necessarily the centroid or the address of a courthouse.

Source and precision

U.S. Census Bureau, 2026 Gazetteer Files, Counties. Original ALAND: 1,040,596,791 m²; AWATER: 40,784,319 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.

Download the official county source ZIP ↗ · Methodology

Common questions

How many acres of land are in Louisa County?

The land measurement converts to approximately 257,137 acres. Including water, total area is approximately 267,215 acres. One square mile equals 640 acres.

Why might another source show a different area?

Check whether it reports land or total area, its Census vintage, and its rounding. Our guide explains how to reconcile county area figures.

Can this establish a property boundary?

No. Statistical measurements and generalized maps do not establish property lines. Consult the relevant local surveying or land-records authority.

Cite this county

Download the complete CSV or JSON dataset