|— City —|
|• Total||0.5 sq mi (1.3 km2)|
|• Land||0.5 sq mi (1.3 km2)|
|• Water||0.0 sq mi (0.0 km2)|
|Elevation||1,575 ft (480 m)|
|• Density||262.1/sq mi (101.2/km2)|
|Time zone||Central (CST) (UTC-6)|
|• Summer (DST)||CDT (UTC-5)|
|GNIS feature ID||1364256|
O'Brien is located at .(33.379922, -99.841812)
According to the United States Census Bureau, the city has a total area of 0.5 square miles (1.3 km2), all of it land.
As of the census of 2000, there were 132 people, 54 households, and 32 families residing in the city. The population density was 262.1 people per square mile (101.9/km²). There were 71 housing units at an average density of 141.0/sq mi (54.8/km²). The racial makeup of the city was 61.36% White, 0.76% Native American, 37.88% from other races. Hispanic or Latino of any race were 55.30% of the population.
There were 54 households out of which 24.1% had children under the age of 18 living with them, 46.3% were married couples living together, 9.3% had a female householder with no husband present, and 40.7% were non-families. 38.9% of all households were made up of individuals and 24.1% had someone living alone who was 65 years of age or older. The average household size was 2.44 and the average family size was 3.34.
In the city the population was spread out with 25.0% under the age of 18, 10.6% from 18 to 24, 15.9% from 25 to 44, 23.5% from 45 to 64, and 25.0% who were 65 years of age or older. The median age was 44 years. For every 100 females there were 71.4 males. For every 100 females age 18 and over, there were 59.7 males.
The median income for a household in the city was $17,500, and the median income for a family was $18,750. Males had a median income of $25,000 versus $13,214 for females. The per capita income for the city was $10,422. There were 22.2% of families and 18.7% of the population living below the poverty line, including 20.0% of under eighteens and 16.7% of those over 64.
The City of O'Brien is served by the Knox City-O'Brien Consolidated Independent School District.
O'Brien is home to the first Texas six-man state championship in 1972.
- "American FactFinder". United States Census Bureau. Retrieved 2008-01-31.
- "US Board on Geographic Names". United States Geological Survey. 2007-10-25. Retrieved 2008-01-31.
- "US Gazetteer files: 2010, 2000, and 1990". United States Census Bureau. 2011-02-12. Retrieved 2011-04-23.