U.S. Customs and Border Protection has been running checkpoints in New Hampshire more frequently under the Trump administration, setting up on Interstate 93 near the small towns of Woodstock and Lincoln. The stated goal of these stops is enforcing immigration law, and to that end, they have been fairly successful. Agents have arrested more than 50 people over the past two years who they determined to be in the country illegally. But those in support of the stops are often quick to turn attention to a topic other than immigration: drugs and the state’s opioid crisis.Here in New Hampshire, despite the political divide on immigration issues, checkpoints are broadly accepted by at least one measure. Roughly 70 percent of residents said they supported the stops as a check on immigration, and to investigate potential drug smuggling, in a survey conducted last year by researchers at the University of New Hampshire.