By JONATHAN J. COOPER and ADRIANA GOMEZ LICON SIERRA VISTA, Ariz. (AP) — Donald Trump is traveling to the shrub-dotted hills of Arizona near the U.S.-Mexico border to campaign Thursday on immigration, his signature issue since launching his first successful presidential bid nine years ago. The visit is the fourth in a series of events held in battleground states this week to try to draw the focus away from Democrats’ celebration of Vice President Kamala Harris’ presidential nomination in Chicago.