the recent floods iestimated to be at least $3 billion. >> sreenivasan: last month, when novelist don winslow published "the border," the final nol in his bestselling trilogy about america's drug wars, the "new york times"aid it landed right on the culture's front- burner. as much as anyone, winslow has charted the decades-long link between the power of the drug cartels and the flood of immigrants seeking a new life, and between what the author considers failed policy and countless deaths and ruined lives. newshour weekend special correspondent jeff greenfield recently visited don winslow at his southern california home-- fittingly, not far from the mexican boreer. >>dent trump's most popular talking points in the last few weeks, the ns of thousands of central american migrants headed toward the u.s. southern border. >> reporter: it has dominated our political debate... !> build that wa build that wall! >> reporter: it helped elect a president. >> president trump, you will not t your wall. >> reporter: it triggered a month-long government shutdown. >> hey, hey, ho, ho! shutdown's got to go! >

we have don winslow and contributor victoria defrancesco. victoria, let's start with you on this.u seeing? you heard the president's messaging, two more caravans, a threat to shut down the u.s./mexico border in total. >> let me focus on the last piece, richard. because if the border were to be shut down, i can't emphasize enough how disastrous this would be. we see on a daily basis about 1.5 billion in terms of cross-border commerce per day. so if you remember a couple of months back in november, the border was shut down for about three, four hours in san diego and that cost us about $5 million just in those couple of hours. so there is the huge economic loss and then you layer on top of that the fact that that is not going to do anything to stem the undocumented crossings that we're seeing because these individuals are folks who go to the ports of the entry to try to apply for asylum. they're metered away and not allowed to process their asylum claims and they are desperate so they try to cross the border in present ports of entry so this will do nothing to stem the tide. and fin