CALLAGHAN, TEXAS. Callaghan (Callahan) was established in 1881 as a cattle shipping point on the International and Great Northern Railroad in Webb County. The settlement was named for Charles Callaghan of the Callaghan Ranch. A post office operated there under the name Callahan in 1880–81. The Callaghan Ranch was still operating in the 1980s, but by that time the community was gone.