A deal Canada struck this year to stem the flow of asylum seekers entering from the U.S. was, at first glance, a quick success: Within days, the number of people caught at unofficial crossings along the border dwindled to a trickle. But five months later, the overall number of people filing refugee claims in Canada has risen instead of falling. The numbers show how hard it is for countries to shut the door on desperate people and the challenge unexpected numbers of asylum seekers can pose: In Toronto, hundreds slept on the streets this summer as they struggled to find beds.