According to the United States Census Bureau, the city has a total area of 215.0 km² (83.0 mi²). 208.2 km² (80.4 mi²) of it is land and 6.8 km² (2.6 mi²) of it is water. The total area is 3.16% water.
As of the census of 2000, there are 139,722 people, 38,174 households, and 32,180 families residing in the city. The population density is 671.0/km² (1,737.8/mi²). There are 42,323 housing units at an average density of 203.2/km² (526.4/mi²). The racial makeup of the city is 81.65% White, 0.41% African American, 0.42% Native American, 0.54% Asian, 0.03% Pacific Islander, 14.66% from other races, and 2.29% from two or more races. 91.28% of the population are Hispanic or Latino of any race.
There are 38,174 households out of which 50.1% have children under the age of 18 living with them, 59.3% are married couples living together, 20.9% have a female householder with no husband present, and 15.7% are non-families. 13.7% of all households are made up of individuals and 6.7% have someone living alone who is 65 years of age or older. The average household size is 3.62 and the average family size is 3.99.
In the city the population is spread out with 34.6% under the age of 18, 11.2% from 18 to 24, 27.5% from 25 to 44, 17.2% from 45 to 64, and 9.5% who are 65 years of age or older. The median age is 28 years. For every 100 females there are 89.0 males. For every 100 females age 18 and over, there are 82.5 males.
The median income for a household in the city is $24,468, and the median income for a family is $26,186. Males have a median income of $21,739 versus $17,116 for females. The per capita income for the city is $9,762. 36.0% of the population and 32.4% of families are below the poverty line. Out of the total people living in poverty, 45.0% are under the age of 18 and 31.0% are 65 or older.
Local attractions include the Gladys Porter Zoo, Camille Lightner Playhouse, a beautiful downtown, TSC/University of Texas at Brownsville, and easy access to South Padre Island and Matamoros, Mexico.