Canada-U.S. border agents try to stem flow of migrants in face of unforgiving weather, vast distances

A bleak panorama of frozen, windblown prairie extends in every direction behind Katy Siemer as she points north, past a barren stand of trees to a pipeline compressor station a few hundred metres away in Manitoba.

The U.S. Border Patrol agent is standing alongside a similar facility in Minnesota that she says undocumented migrants use as a meeting spot when sneaking over from Canada, usually under cover of darkness.

At the moment, it’s a blindingly bright, sunny day, beautiful in every respect but the –29 C temperature.

“Oh, this is very mild,” says Siemer, the deputy patrol agent in charge of