Shamrock is located east of Amarillo on US 83 and I-40 on the banks of the North Fork of the Red River near the Texas/Oklahoma state line, in Wheeler County.
In 1890 the post offic was first established. It was located in the dugout home of George Nickel, an Irish sheep rancher.
In 1984 Shamrock reported a total of ninety-five businesses. Cattle, agriculture, gas, and petroleum continued to be primary in the economy.
Ever since Glen Truax, the town bandmaster, started the tradition in 1938, Shamrock has had a St. Patrick's Day celebration on the weekend nearest March 17. A fragment of the genuine Blarney Stone from Blarney Castle in County Cork, Ireland, is mounted on a pillar in Elmore Park.
In 1990 the population of Shamrock was reported as 2,286.