FILE - This April 16, 1939 file photo shows the dedication of an an altar-like monument on the international border between the United States and Mexico at Lochiel, Ariz., commemorating the 400th anniversary of the arrival of Fray Marcos de Niza, pioneering Franciscan friar, in what is now Arizona. Presumptive GOP nominee Donald Trump's push for a border wall is not a new idea, and since World War I, has been pursued often. Historians say opponents of Mexican immigration have advocated for a wall off and on for about 100 years with little results due to changing technologies and pressure to divert enforcement attention elsewhere. (AP Photo/File)