O Brien County, IA Population

Overview

14,139

Total Population

40.7

Median age

49.74%

Female population %

101:100

Gender ratio (M:F)

60-64 years

Largest age group

67.3

Total dependency ratio

White

Largest racial group

778

Hispanic population

Sources: U.S. Census Bureau, American Community Survey (ACS) 2021

TABLE OF CONTENTS

Age

O Brien County's population is old compared to the rest of the country:

The median age in O Brien County is 40.7, compared to 38.8 nationwide, according to the American Community Survey 2017 - 2021 5 Year estimates.
O Brien County's population under 18 was 24.08%, compared to the 22.51% nationwide.
O Brien County's elderly or the senior population (over 65 age) was 20.29% as compared to 16.04% nationwide.
Of the total population in O Brien County, 19.92% were under the age of 15, 17.89% aged 15 to 29, 41.89% aged 30 to 64, 15.72% aged 65 to 84, and 4.57% were 85 years of age and older.

There are 73 less females than males in O Brien County:

The female percentage in the USA is 50.50% while the male percentage is 49.50%, compared to 49.74% females and 50.26% males in O Brien County, IA.
The O Brien County, IA gender ratio is 101:100 i.e. 101 men to 100 women (1.010).
For male population, the largest age group is 5-9 years with a population of 549.
For the female population, the largest age group is 60-64 years with a population of 521.

O Brien County's population has become increasingly diverse:

Racial distribution of O Brien County population: 92.89% are White, 1.61% are Black or African American, 0.43% are American Indian and Alaska Native, 0.66% are Asian, 2.32% are some other race and 2.09% are multiracial.
O Brien County's racial breakdown clearly shows that there is an absolute majority of White population in the county.
By ethnicity, 778 is Hispanic or Latino (of any race), and 13,361 (94.50% of the total population) is Non-Hispanic.
The largest racial group in O Brien County is White with a population of 13,134 (92.89% of the total population).

O Brien County's population has already reached its peak and is showing a trend of decline:

The peak population was 15,036 in the year 2000
From 2000 to 2010, O Brien County's population decreased by 631 (4.20%), as compared to the national growth of 9.63%.
From 2010 to 2020, O Brien County's population decreased by 251 (1.74%), according to Census Bureau's Population Estimates Program. For the same period, the rate of growth for the United States was 7.17%.
Between the year 2000 and 2022, O Brien County's population was lowest in year 2017 at 13,777.