O'Brien County, IA demographics:
population, income, and more

Total population
17,147
1.5% year-over-year change
Median household income
$70,978/yr
-5.1% year-over-year change
Housing units
7,673
1.9% year-over-year change

O'Brien County population

How many people live in O'Brien County

O'Brien County is home to 17,147 residents, according to the most recent Census data. Gender-wise, 50.8% of O'Brien County locals are male, and 49.2% are female.

Total population
17,147
1.5% year-over-year change
Gender ratio
Male
50.8%
8,705
Female
49.2%
8,442
Value Percent YoY change
Male 8,705 50.8% 2.1%
Female 8,442 49.2% 0.8%
A higher population often means more rental variety and livelier areas. The gender balance—how many men live here compared to women—can reveal a lot about the community and the lifestyles of its residents. Use this info to get a sense of the area's pace and personality.

Age demographics

The median age in O'Brien County is 40, with the population distributed as follows: about 20.6% are children under 15, then 11.8% are in the 15 to 24 age group. Adults between 25 and 44 make up 24.7% of the population, while another 22.1% fall into the 45 to 64 bracket. Finally, around 20.8% are 65 or older.

Median age
40
Age breakdown
Under 15
20.6%
15 to 24
11.8%
25 to 44
24.7%
45 to 64
22.1%
Over 65
20.8%
Value Percent YoY change
Under 15 3,539 20.6% 0.4%
15 to 24 2,018 11.8% 1.7%
25 to 44 4,235 24.7% 3.6%
45 to 64 3,795 22.1% -1.2%
Over 65 3,560 20.8% 3.0%
The age composition helps you get insight into who lives in the area. A younger population might mean a more active, fast-paced vibe, while an older one could suggest a quieter, slower lifestyle. If there's a balanced makeup, you’re likely to find a variety of services, housing types, and community spaces that cater to different life stages.

Racial makeup

In O'Brien County, 94% of the population are US-born citizens, while 3.2% have gained naturalized citizenship. At the same time, 2.8% of residents are non-citizens. As for race, 88.2% of locals are Caucasian, 1.5% are African American and 0.6% have Asian roots. Another 0.4% are Indigenous American, 0.1% are Pacific Islanders, while 3.6% identify as another race. There’s also a share of 5.6% that includes residents with two or more races.

Citizenship
U.S.-born citizens
94%
Non-U.S.-born citizens
3.2%
Non-citizens
2.8%
Value Percent YoY change
U.S.-born citizens 16,116 94% 1.1%
Non-U.S.-born citizens 542 3.2% 3.2%
Non-citizens 489 2.8% 15.6%
Racial breakdown
White
88.2%
Black or African American
1.5%
American Indian and Alaska Native
0.4%
Asian
0.6%
Native Hawaiian and other Pacific Islander
0.1%
Two or more races
5.6%
Other
3.6%
Value Percent
White 15,117 88.2%
Black or African American 256 1.5%
American Indian and Alaska Native 64 0.4%
Asian 103 0.6%
Native Hawaiian and other Pacific Islander 22 0.1%
Two or more races 961 5.6%
Other 624 3.6%

Households in O'Brien County

A peek inside O'Brien County households

O'Brien County has 6,867 households, with an average of 3 members in each. Of these, 66% are families, while the remaining 34% are made up of individuals living alone or with non-relatives, such as roommates.

Households stats

Total households
6,867
1.5% year-over-year change
Average people per household
3
Non-family households
2,333
Family households
4,534
Value Percent YoY change
Non-family households 2,333 34% -0.5%
Family households 4,534 66% 2.6%
The mix between family and non-family households gives a glimpse into daily life. A higher percentage of families might mean more parks and schools, while more non-family setups can mean flexible housing and diverse living styles. For renters, this can signal what kinds of homes are common and can help you figure out if the area matches your lifestyle.

Housing in O'Brien County

The housing landscape of O'Brien County

O'Brien County's housing consists of 7,673 units, with 84.2% being detached single-family homes ideal for those wanting space. Attached options, including duplexes and townhouses, make up 2.9% and offer a more compact, shared living style. Then there are the multifamily buildings in the area, and for those seeking flexibility, non-traditional options like mobile homes account for 2.1% of the housing landscape.

Housing units
7,673
1.9% year-over-year change
Housing types
Value Percent
1 unit, detached 6,457 84.2%
1 unit, attached 221 2.9%
2 units 68 0.9%
3 or 4 units 214 2.8%
5 to 9 units 194 2.5%
10 to 19 units 125 1.6%
20 to 49 units 176 2.3%
50 or more units 57 0.7%
Mobile home 161 2.1%
Homes built since 2020
53
1,666.7% year-over-year change

The age of buildings in O'Brien County

In O'Brien County, the median construction year is 1956. About 29.1% of homes were built before the 1940s, with another 6.8% going up by 1949. Most development happened in the second half of the 20th century. Then, 6.4% of homes were added from 2000 to 2009, 3.9% between 2010 and 2019, and 0.7% are part of the newest wave of development.

Construction year breakdown by decade
Value Percent YoY change
Built in 1939 or earlier 2,235 29.1% -0.2%
Built between 1940 and 1949 524 6.8% 9.8%
Built between 1950 and 1959 1,217 15.9% -3.3%
Built between 1960 and 1969 752 9.8% 4.7%
Built between 1970 and 1979 1,038 13.5% 11.1%
Built between 1980 and 1989 543 7.1% -4.9%
Built between 1990 and 1999 521 6.8% -10.6%
Built between 2000 and 2009 488 6.4% 9.7%
Built between 2010 and 2019 302 3.9% -0.3%
Built in 2020 or later 53 0.7% 1,666.7%
As a renter, knowing when homes were built helps you understand the potential condition and design of rental units. Newer builds may have more contemporary layouts, while older homes can offer character or larger lots, depending on the area.

O'Brien County occupancy rates

Out of the 6,867 occupied housing units in O'Brien County, 78.1% are owner-occupied, while 21.9% are lived in by tenants. Meanwhile, 10.5% of all homes on the local market sit vacant.

Occupied housing units
6,867
1.5% year-over-year change
Occupancy breakdown
Renter occupied
1,501
Owner occupied
5,366
Value Percent YoY
change
Renter occupied 1,501 21.9% 6.5%
Owner occupied 5,366 78.1% 0.2%
Unoccupied housing units
10.5%
Unoccupied housing units refer to homes that are currently without residents—whether they're waiting for renters or owners, used seasonally, or simply unclaimed. A higher share of empty homes may mean more housing availability, while a low number can reflect a tighter market with more competition. This, along with the renter-vs.-owner mix, helps paint a clearer picture of what types of housing and services are likely to be available in the area.

O'Brien County housing costs

Housing costs in O'Brien County come to a median of $798 per month, while tenants specifically pay a median gross rent of $750.

Median housing costs per month
$798/month
This figure sums up typical monthly housing costs for all households in the area. If you own, it includes mortgage payments in addition to property taxes, insurance and HOA fees. If you rent, it accounts for rent plus extras like utilities. It’s useful for seeing how local living expenses stack up compared to other places.
Median gross rent in O'Brien County
$750/month
Gross rent gives a more complete look at what renters actually pay, including not just base rent, but also utilities and fees. It’s a key number for evaluating rental affordability in your area of interest and understanding how it compares to nearby locations.

Education in O'Brien County

O'Brien County education at a glance

About 40.1% of the population in O'Brien County went to high school, while 20.5% pursued college studies. Another 16% earned an associate degree and 16.7% hold a bachelor’s. Meanwhile, 4.1% went even further, earning a master’s or doctorate.

Education level
Value Percent YoY change
No high school 334 2.6% 15.6%
High school diploma 5,151 40.1% -4.1%
College diploma 2,636 20.5% 5.4%
Associate degree 2,060 16% 8.0%
Bachelor's degree 2,144 16.7% 4.3%
Graduate degree 532 4.1% 0.2%
A community’s education mix can offer insights into the local economy and housing market. Higher levels of education often align with more job opportunities and stable incomes, which can increase demand for homes and influence both rent prices and rental availability.

Income in O'Brien County

How much people earn in O'Brien County

The average annual household income in O'Brien County was $87,409 in 2024, the most recent annual data available, according to the U.S. Census Bureau. This marked a -0% change from the previous year. At the same time, the median income stood at $70,978, reflecting a -5.1% shift over the same period.

Average household income in O'Brien County
$87,409/year
-0.0% year-over-year change
Median household income in O'Brien County
$70,978/year
-5.1% year-over-year change

O'Brien County income by age

In O'Brien County, households led by residents aged 25 to 44 — usually in the early to mid stages of their careers — have a median income of $93,952. Those with someone between 45 and 64 in charge, often well established professionally, earn $94,327 overall. Younger households, where the main provider is under 25 and just starting out, report a median income of $56,412, while those led by someone over 65, many of whom may be retired, have about $46,250 in earnings. Overall, 87.3% of the locals in this community live above the poverty line.

Income breakdown by age
Value YoY change
Under 25 $56,412 22.0%
25 - 44 $93,952 16.3%
45 - 64 $94,327 -0.3%
Over 65 $46,250 5.7%
Above poverty level
14,464
Below poverty level
2,099
Value Percent YoY
change
Above poverty level 14,464 87.3% 1.8%
Below poverty level 2,099 12.7% -1.0%

Employment in O'Brien County

Workforce and job types in O'Brien County

66.9% of the working population are employed in professional or administrative positions, while 33.1% are in hands-on or service-based jobs. Also, 16.4% run their own businesses, 63.2% are employed by private companies, and 11.5% work in the public sector.

Workforce demographics

White collar
5,823
Blue collar
2,876
Value Percent YoY change
White collar 5,823 66.9% 3.0%
Blue collar 2,876 33.1% 2.4%
Employer type
Self employees
16.4%
Private companies
63.2%
Governmental workers
11.5%
Not for profit companies
8.8%
Value Percent YoY change
Self employees 1,430 16.4% 9.2%
Private companies 5,500 63.2% 0.8%
Governmental workers 1,000 11.5% 1.5%
Not for profit companies 769 8.8% 7.7%

Transportation in O'Brien County

How people get around in O'Brien County

In O'Brien County, the average commute time is 16 minutes. Commuting methods vary: 96.4% of residents travel by personal vehicle and 3.1% prefer to walk, while the remaining share relies on public transit or on two wheelers to get from A to B.

Commute time
16 min
0.0% year-over-year change
Means of transportation
Value Percent YoY change
Car 7,454 96.4% 0.5%
Bus or trolleybus 19 0.2% 533.3%
Ferryboat 5 0.1% 25.0%
Motorcycle 3 0% N/A
Bicycle 10 0.1% 0.0%
Walk 241 3.1% 28.2%
Understanding how locals get to work can help you plan your own routine. High car usage might mean you’ll need a vehicle, while strong public transit or walkability could save you the hassle. Commute times also play a big role in quality of life—shorter trips can give you more time for the things you enjoy.

What is the median and average household income in O'Brien County by zipcode?

Zipcode Population Number of households Median income Average income
51201 6,430 2,550 $68,799 $83,846
51231 562 141 $108,058 $97,427
51238 1,502 556 $74,000 $90,449
51245 1,377 475 $69,531 $82,733
51248 1,534 686 $64,375 $82,772
51346 2,247 963 $72,426 $84,500
51009 113 50 $58,750 $85,182
51022 960 385 $96,505 $97,016
51046 1,326 637 $84,125 $94,251
51058 1,096 424 $63,036 $75,915

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FAQs about O'Brien County demographics 

What is the total population of O'Brien County?

O'Brien County has a total population of 17,147 residents, according to the latest release from the U.S. Census Bureau: the 2019-2023 American Community Survey (ACS) 5-year estimates. This figure changed by +1.5% compared to a year ago.

What is the gender ratio in O'Brien County?

The gender ratio in O'Brien County is as follows:
  • 50.8% males (8,705 residents)
  • 49.2% females (8,442 residents)

What is the median age in O'Brien County?

The median age in O'Brien County is 40.

What is the age distribution of the population in O'Brien County?

The age distribution in O'Brien County is as follows:
  • Under 15: 20.6% (3,539 residents)
  • Ages 15-24: 11.8% (2,018 residents)
  • Ages 25-44: 24.7% (4,235 residents)
  • Ages 45-64: 22.1% (3,795 residents)
  • Over 65: 20.8% (3,560 residents)

What is the racial and ethnic makeup of O'Brien County?

The racial and ethnic makeup of O'Brien County is as follows:
  • White: 88.2% (15,117 residents)
  • Black or African American: 1.5% (256 residents)
  • American Indian and Alaska Native: 0.4% (64 residents)
  • Asian: 0.6% (103 residents)
  • Native Hawaiian and Other Pacific Islander: 0.1% (22 residents)
  • Two or More Races: 5.6% (961 residents)
  • Other: 3.6% (624 residents)

What percentage of the population in O'Brien County are U.S.-born citizens?

U.S.-born citizens represent 94% of the population in O'Brien County.

How many housing units are there in O'Brien County?

There are 7,673 housing units in O'Brien County, reflecting a +1.9% change compared to the previous year, according to the latest data from the U.S. Census Bureau.

How many households are in O'Brien County and what is the average household size?

O'Brien County has a total of 6,867 households, with an average of 3 people in each.

What is the median household income in O'Brien County?

O'Brien County has a median household income of $70,978, representing a -5.1% shift from the previous year, according to the U.S. Census Bureau.

What is the job market overview for O'Brien County?

Here’s a detailed breakdown of the local job market:

Job types:
  • White-collar workers: 66.9% (5,823 residents)
  • Blue-collar workers: 33.1% (2,876 residents)

Places of employment:
  • Self-employed: 16.4% (1,430 residents)
  • Private companies: 63.2% (5,500 residents)
  • Governmental workers: 11.5% (1,000 residents)
  • Not-for-profit companies: 8.8% (769 residents)

Data source & methodology

The demographic data on this page was sourced from the latest U.S. Census Bureau release—the 2019–2023 American Community Survey (ACS) 5-year estimates.

The information, issued annually, is compiled and published by the Point2Homes Research Team as soon as new data becomes available.

No representation, guarantee, or warranty is made concerning the accuracy or completeness of modified or aggregated information for particular areas.

Page last updated: September 2025