The city takes its name from a playa, a unique dryland plains geographic feature situated atop the divide between the Rio Grande and Colorado River watersheds, located less than two miles south of the city, through which St Hwy 137 passes. The playa, with no outlet, is over two sections in size, making it the largest in Texas; it holds water temporarily and only after high runoff rain events, being used for grazing the remainder of the time. Though seasonal and temporal, the 'big playa lake', in wet periods, is significant in a semi-arid, drought-frequented environment and has been utilized regularly as a food and water resource by man and animal, alike, since prehistoric times.
Started as a small ranching community in the late 1880s, Big Lake owes its current existence to the Kansas City, Mexico and Orient Railway, which passed through the area in 1912 as it was extended from Sherwood, west of San Angelo, to Girvin and beyond the Pecos River. The growth from the railroad, coupled with that from the Santa Rita discovery well in 1923, allowed it, in 1925, to take over the position of county seat from Stiles , a pioneer ranching community established in 1894 on Centrailia Draw, approximately 20 miles to the north.
There were 932 households out of which 48.9% had children under the age of 18 living with them, 69.4% were married couples living together, 7.9% had a female householder with no husband present, and 19.4% were non-families. 18.0% of all households were made up of individuals and 7.8% had someone living alone who was 65 years of age or older. The average household size was 3.05 and the average family size was 3.47.
In the city the population was spread out with 34.9% under the age of 18, 7.7% from 18 to 24, 28.3% from 25 to 44, 19.0% from 45 to 64, and 10.2% who were 65 years of age or older. The median age was 32 years. For every 100 females there were 98.1 males. For every 100 females age 18 and over, there were 97.5 males.
The median income for a household in the city was $33,478, and the median income for a family was $37,104. Males had a median income of $31,056 versus $17,656 for females. The per capita income for the city was $12,829. About 8.8% of families and 11.3% of the population were below the poverty line, including 11.7% of those under age 18 and 23.2% of those age 65 or over.