ZIP Codes of Caldwell County, MO

Population & People
Population & People
Total Population
9,107
Household Income
Household Income
Median Income
$58,937
Housing
Housing
Total Housing Units
4,410
Business & Economy
Business & Economy
Total Businesses
162
Employment
Employment
Employment Rate
55.33%
Education
Education
Bachelor's Degree+
18.26%
Source: U.S. Census ACS 2024 5-Year Estimates · rolled up across the 7 ZIPs in this county.
Data Last Updated: June 1, 2026
ZIP Codes:7 ZIP Codes (7 Standard, 0 PO Box, 0 Unique) [See All]
Area Codes:660 / 816 / 975
Timezone:Central (GMT -06:00)
Local Time:2:12:41 PM
Population:9,107 [See All]
FIPS:29025
CBSA:Kansas City, MO-KS
Land Area:553 sq mi
Water Area:3 sq mi
Coordinates:39.6519, -93.9536
Quick Link:
https://www.zip-codes.com/county/mo-caldwell.asp
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Missouri's #88 most populous county
9,107 residents across 7 ZIPs — #88 of 116 Missouri counties.

Standout ZIPs in this County


Most Populous
Hamilton · 2,923 people
32.1% of county total
Highest Income
Polo · $75,455 median
1.3× county average
Largest Land Area
Braymer · 125.7 sq mi
Spans the most ground
Fastest Growth
Polo · -1.5% (10-yr)
2,017 → 1,986 residents
Most Educated
Hamilton · 25.1% bachelor's+
504 of 2,009 adults 25+

Things worth knowing about Caldwell County


9,107 residents live across 7 ZIPs covering 553 sq mi, served by 7 distinct USPS-recognized cities.

Population moved from 9,193 to 9,107 from 2014 to 2024 — a -0.9% change. 2 ZIPs gained residents, 5 lost.

The county's wealthiest ZIP 64671 (Polo, $75,455 median) and poorest ZIP 64625 (Breckenridge, $35,000) are 19.8 miles apart — a 2.2× income gap across local geography.

Median home values vary 3.5× across this county — from $64,300 in 64625 (Breckenridge) to $228,100 in 64649 (Kidder).

Density varies across the county — from 7 people/sq mi in 64637 (Cowgill) to 26 in 64644 (Hamilton).

Educational attainment ranges from 9.2% bachelor's+ in 64625 (Breckenridge) to 25.1% in 64644 (Hamilton) — the breadth of educational profiles across the area.

Within Missouri, this is the #88 most populous of 116 counties and ranks #67 for median household income .

Weighted by population, the typical household earns about $65,074 across the county — reflecting what a typical resident sees, not a simple ZIP average.

18.3% of adults age 25+ hold a bachelor's degree or higher (1,150 of 6,299 reporting).

7 Standard delivery, 0 PO Box only, 0 single-entity Unique ZIPs serve this county.

Stories about Caldwell County


Big & sparse

A frontier county — vast land area with only a few residents per square mile. Daily life looks very different here than in the country's denser counties.

Total area
553
square miles
Avg density
16.5
people per sq mi
Population
9,107
across 7 ZIPs
Braymer
125.7 sq mi
1,489 residents
Hamilton
114.4 sq mi
2,923 residents
Polo
90.2 sq mi
1,986 residents

All ZIP Codes in Caldwell County


ZIPCityTypePopulationMedian IncomeArea (sq mi)10-yr Growth
64644HamiltonStandard2,923$74,408114.4-5.1%
64671PoloStandard1,986$75,45590.2-1.5%
64624BraymerStandard1,489$58,095125.7-11.9%
64649KidderStandard814$67,21638.639.1%
64625BreckenridgeStandard738$35,00064.841.7%
64650KingstonStandard665$45,44145.6-7.0%
64637CowgillStandard492$56,94474.1-15.6%

Adjacent & Nearby Counties