A small portion of land at the eastern end of the county belonged to the Muscogee (Creek) Nation.

In the early years of the oil boom, workers and adventurers flooded into the county, rapidly tripling the population.

Seminole County has been an important part of the Oklahoma and United States petroleum industry for over 80 years.

1 well reached the Wilcox sand at 4073 feet, bringing in the Seminole City Field.

[5] The Maud field, discovered in 1927 by Amerada Petroleum, was the first discovery using reflection seismology.

[6] This marked the beginning of the use of modern geophysical methods in the petroleum industry.

25.90% of all households were made up of individuals, and 13.10% had someone living alone who was 65 years of age or older.

High rates of smoking and obesity for both sexes and a low level of physical activity for males appear to be contributing factors to the relatively short life expectancy.

[16] In 2020, the Robert Wood Johnson Foundation ranked Seminole country as 61st (of 77 counties in Oklahoma) in "health outcomes," as measured by length and quality of life.