County outline
Where Montgomery County is located
Area breakdown
Land accounts for 99% of Montgomery County’s measured area and water for 1%. Its combined area converts to 1,399.9 square kilometers or approximately 345,914 acres.
Green: land · blue: water
| Measurement | Square miles | Square kilometers | Acres |
|---|---|---|---|
| Land | 535.047 | 1,385.765 | 342,430.1 |
| Water | 5.444 | 14.1 | 3,484.2 |
| Total | 540.491 | 1,399.865 | 345,914.2 |
How Montgomery County compares
By original Census land area, Montgomery County ranks #72 of 115 in Missouri and #1953 of 3,222 nationally. National rankings include the 50 states, District of Columbia, and Puerto Rico.
Its land area is 0.904 times the Missouri county-equivalent median of 592 square miles. It accounts for 0.8% of the combined county land area in the state.
See the complete Missouri ranking · What counts as a county equivalent?
Population and density of Montgomery County
The Census Bureau estimates that 11,590 people lived in Montgomery County on July 1, 2025. That ranks #2,382 of 3,222 county equivalents nationally and #79 of 115 in Missouri. Since the April 1, 2020 estimates base of 11,321, the population has grown by 269 (+2.4%), compared with +1.9% for Missouri as a whole.
With 535 square miles of land, that is 22 people per square mile (8.4 per km²), placing Montgomery County #2,264 nationally for density and #78 in Missouri. The median county equivalent has 47 people per square mile; the Missouri median is 31. Put another way, there are about 30 acres of land per resident.
| July 1 | 2020 | 2021 | 2022 | 2023 | 2024 | 2025 |
|---|---|---|---|---|---|---|
| Estimate | 11,293 | 11,450 | 11,471 | 11,464 | 11,556 | 11,590 |
| Change | — | +157 | +21 | −7 | +92 | +34 |
U.S. Census Bureau, Vintage 2025 population estimates. Estimates are revised each year and are not decennial census counts. Density divides the whole population by the whole county’s land area, so it describes an average, not how settlement is distributed within the county. Population sources and methods.
Cities and towns in Montgomery County
9 incorporated places lie at least partly in Montgomery County. Together they are home to 6,218 people (53.6%); the other 5,372 (46.4%) live outside any incorporated place, in unincorporated communities and rural areas.
The largest is Montgomery City city, with 2,782 residents in the county.
| Incorporated place | Population 2025 | Since 2020 | Land mi² |
|---|---|---|---|
| Montgomery City cityCounty seat | 2,782 | −1% | 3.419 |
| Wellsville city | 1,012 | +2% | 1.537 |
| Jonesburg city | 864 | +19% | 2.007 |
| New Florence city | 650 | +1.2% | 3.007 |
| Bellflower city | 337 | +2.4% | 0.559 |
| High Hill city | 186 | −1.1% | 0.46 |
| Middletown town | 169 | −1.2% | 0.321 |
| Rhineland town | 138 | −0.7% | 0.337 |
| McKittrick town | 80 | +1.3% | 0.488 |
Population: U.S. Census Bureau Vintage 2025 subcounty estimates, counting only the part of each place inside Montgomery County. Land: 2026 Census Gazetteer, for the whole place even where it extends into other counties. How communities are listed.
Metropolitan area
Montgomery County is not part of any metropolitan or micropolitan statistical area in the Office of Management and Budget’s July 2023 delineation; 1,306 other county equivalents are also outside one. These areas are built around an urban core of at least 10,000 people plus the counties tied to it by commuting, so counties outside them are generally rural.
ZIP codes
11 ZIP Code Tabulation Areas have land in Montgomery County; 6 of them have most of their land inside the county, and the others mainly cover neighboring areas.
6333363350633516335963361633636338163384650416506965264
ZIP Code Tabulation Areas are the Census Bureau’s approximations of USPS ZIP Code service areas, from the 2020 Census relationship files. Lighter codes have less than half of their land in this county. Post-office-box and single-address ZIP Codes have no tabulation area.
Counties bordering Montgomery County
Montgomery County shares a land border with 7 county equivalents. It has more land than 2 of them. The largest neighbor is Callaway County (834.6 mi²) and the smallest is Warren County (428.6 mi²). Together with its neighbors, Montgomery County forms a block of 4,913 mi² of land, of which it holds 10.9%.
| Bordering county equivalent | Land mi² | Size vs. Montgomery | Compare |
|---|---|---|---|
| Callaway County | 834.6 | 1.6× larger | Compare |
| Audrain County | 692.3 | 1.3× larger | Compare |
| Pike County | 670.4 | 1.3× larger | Compare |
| Lincoln County | 626.6 | 1.2× larger | Compare |
| Osage County | 606.5 | 1.1× larger | Compare |
| Gasconade County | 519 | about the same | Compare |
| Warren County | 428.6 | 1.2× smaller | Compare |
How big is Montgomery County compared with U.S. states?
Montgomery County has less land than any of the 50 states. Rhode Island, the smallest state by land area, has 1,033.9 mi², about 1.9 times as much. Missouri’s county land could hold about 128 areas the size of Montgomery County.
Another way to picture it: the same land area would fill a square about 23.1 miles (37.2 km) on each side. Real county shapes are rarely square, so this is a scale reference rather than a width or driving distance.
State figures are the sums of each state’s county-equivalent land measurements in the same Census release, so states and counties are compared on the same basis. Published state totals can differ slightly because of rounding. Compare all states · Counties bigger than entire states.
What stands out about Montgomery County?
Montgomery County has more land than 1,269 of the other 3,221 county equivalents in the dataset.
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 Montgomery County at #2,039 nationally by total area, 86 places farther from the top than its land rank. Other county equivalents gain more area when their water measurements are included.
Its water share is 1%, compared with a national county-equivalent median of 1.2% — 0.2 percentage points lower. 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 Montgomery County in the national ranking. They can be in different states and are not necessarily geographic neighbors.
| Land rank | County equivalent | Land mi² | Comparison |
|---|---|---|---|
| #1952 | Etowah County, Alabama | 535.1 | Compare |
| #1953 | Montgomery County, Missouri | 535 | This county |
| #1954 | Page County, Iowa | 534.9 | Compare |
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 38.935184, -91.465427. 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: 1,385,765,123 m²; AWATER: 14,100,641 m². Rankings use ALAND; exact ties use ascending GEOID. Tables preserve Census-published square miles to three decimals, with conversions based on those values.
Common questions
How big is Montgomery County?
Montgomery County, Missouri has 535 square miles (1,385.8 km²) of land and 5.444 square miles of water, for a total area of 540.5 square miles. It ranks #1953 of 3,222 U.S. county equivalents by land area.
Is Montgomery County the largest county in Missouri?
No. Montgomery County ranks #72 of 115 in Missouri by land area. The largest is Texas County, with 1,177.3 square miles of land.
What counties border Montgomery County?
Montgomery County shares a land border with Warren County, Callaway County, Audrain County, Gasconade County, Lincoln County, Pike County, and Osage County.
What is the population of Montgomery County?
The Census Bureau estimates Montgomery County had 11,590 residents on July 1, 2025, ranking #2,382 of 3,222 county equivalents. That is 22 people per square mile of land.
What is the county seat of Montgomery County?
The county seat of Montgomery County is Montgomery City.
What cities and towns are in Montgomery County?
Montgomery County has 9 incorporated places. The most populous five are Montgomery City city, Wellsville city, Jonesburg city, New Florence city, and Bellflower city; 5,372 residents live outside any incorporated place.
Is Montgomery County part of a metropolitan area?
No. Montgomery County is outside every metropolitan and micropolitan statistical area in the July 2023 OMB delineation.
How many ZIP codes are in Montgomery County?
11 ZIP Code Tabulation Areas have land in Montgomery County, and 6 of them have most of their land inside the county. Census ZIP Code Tabulation Areas approximate USPS ZIP Code areas.
How does Montgomery County compare with U.S. states?
It has less land than every state. Rhode Island, the smallest, has 1.9 times as much land.
How many acres of land are in Montgomery County?
The land measurement converts to approximately 342,430 acres. Including water, total area is approximately 345,914 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.