DERBY LINE, Vt. (AP) — Hundreds of border agents from across the U.S. are being temporarily transferred south ahead of the busy summer tourism season, worrying those along the northern border who rely on cross-border commerce — including U.S. innkeepers, shop owners and restaurateurs who fear their Canadian customers could be caught in backups at border crossings.

U.S. Customs and Border Protection says 731 northern border agents from land, sea and airports are in the process of being sent to the U.S.-Mexico border, where they will help handle the influx of families and unaccompanied children from Central America.

The move comes as businesses gear up for the summer season, when tens of thousands of Canadian tourists help buoy the economies of communities in border states and elsewhere deeper inside the United States.

Last week, 13 bipartisan members of Congress from six northern border states, including Washington, wrote acting Homeland Security Secretary Kevin McAleenan, voicing concerns the plans could hurt cross-border travel and commerce.

The letter was signed by four members of Congress from New York, four from Michigan, two from New Hampshire, and one each from Minnesota, Washington and North Dakota.

While CBP wouldn’t specify where the agents are coming from, they are being drawn from 328 ports of entry.