AARON HEITKE, who heads the border patrol in Grand Forks, North Dakota, would like the federal government to send more money his way. Just over 2,000 agents patrol America’s northern border, compared with 17,000 down south. Mr Heitke wants some of them to come up and lend a hand. Heidi Heitkamp, a Democratic senator from North Dakota who co-authored the Northern Border Security Review Act, signed into law by then-President Barack Obama in December, would like more federal dollars for her state, too. The world’s longest land border, running through Montana’s mountains, four Great Lakes, glorious woods and wild prairies, is also one of the least patrolled and surveyed. Some see Donald Trump’s election as a chance to change that.

Between 2000 and 2010 taxpayers spent an estimated $90bn on the southern border, which included paying the salaries of guards, building fences, x-ray machines that can peer into cargo trains and trucks, tower-mounted cameras, ground sensors, predator drones and drug-sniffing dogs. Expenditure on the northern border in the same period was in the millions rather than billions. Yet the northern border sees the world’s largest bilateral daily flow of goods and people, on average $190m and nearly 400,000 respectively. It offers more opportunities for illegal crossings: in many places a small white obelisk somewhere in a field is the only marker of the border. Some streets and buildings are shared between Canada and America. On the north side of Canusa Street in Vermont (Rue Canusa in Québécois) lies Canada; to the south is America. The Haskell Free Library and Opera House straddles both countries.

If America is to spend even more on border security, would marginal dollars be better spent on the northern border than the southern one? If the main purpose is to nab illegal immigrants, the answer is no. In 2016 border-patrol agents caught only 2,300 illegal migrants on the northern border, compared with almost 200 times as many (408,000) on the southern one. If the purpose is to prevent drug-smuggling, the case is a bit stronger. The DEA reports that lots of marijuana and ecstasy enters from the north, though in total the quantity of drugs seized is much lower: 700lb (318kg) of cocaine and marijuana in the north versus 1.7mlb in the south.

Those who see the northern border as alarmingly porous worry about terrorists crossing it, too. About the same number of Canadians and Americans joined IS in Syria, which suggests that Canada has a bigger problem with home-grown jihadists (who might go south), points out Bruce Hoffman of Georgetown University.

For their part, Canadians are as fixated on their border with America as Americans are on theirs with Mexico, says Nik Nanos, a Canadian pollster. Ninety percent of Canada’s population lives within a 90-minute drive of it. Some have started to fret about asylum-seekers crossing from America into Canada illegally to escape the immigration policies of the new administration. (If they crossed legally, at official border posts, they would be turned away under agreements between America and Canada, which say that refugees must request protection in the first safe country they arrive in.) Their numbers are small, in the hundreds perhaps, though this could change in the warmer months. Canadians continue to show their traditional generosity of spirit towards asylum-seekers, says Mr Nanos, but they also dislike people jumping the queue. All of which shows that it is usually easier to make the argument for harder borders than for more open ones.