Bay City, the county seat of Matagorda County, is an incorporated city at the junction of State Highways 35 and 60, in the north central portion of the county seventy-eight miles southwest of Houston. According to the United States Census Bureau, the city has a total area of 8.5 square miles (22.0 km2), of which 8.5 square miles (22.0 km2) is land and 0.12% is covered by water. Bay City was formerly named "Bay Prairie", as the natural ecosystems that surround the town are prairies crisscrossed by creeks that lead into the bay.
As of the census of 2000, 18,667 people, 6,912 households, and 4,769 families resided in the city. The population density was 2,196.0 people per square mile (847.9/km2). There were 8,113 housing units at an average density of 954.4 per square mile (368.5/km2). The racial makeup of the city was 61.62% White, 17.26% African American, 0.74% Native American, 0.88% Asian, 0.07% Pacific Islander, 16.84% from other races, and 2.59% from two or more races. Hispanics or Latinos of any race were 34.74% of the population. Of the 6,912 households, 37.9% had children under the age of 18 living with them, 49.0% were married couples living together, 16.1% had a female householder with no husband present, and 31.0% were not families. About 27.1% of all households were made up of individuals, and 10.5% had someone living alone who was 65 years of age or older. The average household size was 2.66 and the average family size was 3.25.
In the city, the population was distributed as 30.9% under the age of 18, 9.8% from 18 to 24, 28.2% from 25 to 44, 20.0% from 45 to 64, and 11.1% who were 65 years of age or older. The median age was 32 years. For every 100 females, there were 95.0 males. For every 100 females age 18 and over, there were 91.1 males. The median income for a household in the city was $30,446, and for a family was $39,281. Males had a median income of $38,202 versus $23,058 for females. The per capita income for the city was $15,284. About 18.3% of families and 21.4% of the population were below the poverty line, including 27.7% of those u