Crossing a state line on one of the American interstate roads, drivers are normally greeted by a variety of signs. They may advertise the delights awaiting the visitor – ‘10,000 LAKES’ or ‘FAMOUS POTATOES’ plus instructions about local speed limits. And normally, as the coup de grâce, ‘BUCKLE UP’.

Travelling north in New England on the I-95 and passing from Massachusetts into New Hampshire the message is more discreet.