By Christina Goldbaum and Yaqoob Akbary; Photographs by Kiyana Hayeri @ NYTimes.com, Updated Feb. 3

ZARANJ, Afghanistan — [....]

Since the United States withdrew troops and the Taliban seized power, Afghanistan has plunged into an economic crisis that has pushed millions already living hand-to-mouth over the edge. Incomes have vanished, life-threatening hunger has become widespread and badly needed aid has been stymied by Western sanctions against Taliban officials.

More than half of the population is facing “extreme levels” of hunger, António Guterres, United Nations secretary-general, said last month. “For Afghans, daily life has become a frozen hell,” he added.

Now with no immediate respite in sight, hundreds of thousands of people have fled to neighboring countries.

From October through the end of January, more than a million Afghans in southwestern Afghanistan alone have set off down one of two major migration routes into Iran, according to migration researchers. Aid organizations estimate that around 4,000 to 5,000 people are crossing into Iran each day [....]

[....] David Mansfield, a researcher tracking Afghan migration. By his estimates, up to four times as many Afghans were leaving Afghanistan for Pakistan and then Iran each day in January compared with the same time last year [...]