That's some good ol' country blues. Compare these examples (literally the first two that came up in a search for that term on YouTube):
Country blues is a direct descendant of the original folk and rural blues styles that represented an early American adaption of African musical styles and aesthetics, via African-American communities in the rural South. The adaption of folk blues to urban big bands was the birth of jazz. A generation or so later, an electrified urban version of the blues was the direct forerunner of rock and roll.
The original style was absorbed into the country-western music tradition, and has come to be a common soundtrack shorthand to indicate a sleepy rural or Western town. (See this question for more about the much wider Country-Western genre.) Although folk blues was originally an African-American style, it's rarely heard these days outside of the predominantly white country-western genre, where it is frequently incorporated into country rock.