[1] SH 131 begins at US 277, 12 miles north of Eagle Pass near Maverick County Memorial International Airport.

[2] The route travels roughly to the north-northeast through unincorporated sections of Maverick and Kinney counties; the only incorporated community between the route's termini is the city of Spofford.

[3] SH 131 was originally designated on January 18, 1928 from Brackettville to Spofford.

[5] On July 15, 1935, the extension south of Spofford was cancelled.

[6] The extension south of Spofford was restored on November 24, 1936.