TENARES, Dominican Republic — The night that William Lantigua was elected the first Latino mayor in Massachusetts history, people in this remote city surrounded by cocoa farms and coffee plantations felt as if they had won, too. For months in 2009, Tenares residents had called and e-mailed friends and relatives in the city of Lawrence, almost 2,000 miles away, urging them to vote for Lantigua. “He wouldn’t have won without the support from Tenares,’’ said Fermin Tejada, a councilor in this city which has sent hundreds, if not thousands, of residents to live in Lawrence since the 1960s. Tejada said...