In 1949 and 1950, the Giants played as members of the Class D level Rio Grande Valley League, hosting home games at Paris Field.
The Giants were preceded by the 1938 McAllen Packers, who played as members of the Class D level Texas Valley League, reforming after a nine–season hiatus.
[5][6][1] The McAllen "Giants" joined the six-team Class D level Rio Grande Valley League, with the Brownsville Charros, Corpus Christi Aces, Del Rio Cowboys, Donna Cardinals and Laredo Apaches beginning league play with McAllen on April 27, 1949.
[8] In their first season of play, the 1949 McAllen Giants qualified for the four-team Rio Grande Valley League playoffs.
[11][12][1] The 1950 McAllen Giants finished a distant last in the Rio Grande Valley league final standings.