A long-standing view in labor history holds that the northern migration of American workers in the early twentieth century was driven chiefly by the pull of industrial wages. Recent quantitative work reorders this picture. Analyzing county-level records, economists find that departures spiked most sharply where the boll weevil had devastated cotton yields—often a year or two before any wage signal from northern factories could plausibly have reached rural households. The finding does not overturn the wage explanation so much as resequence it: environmental shocks appear to have set families in motion, after which wage differences shaped where they settled. The migration, on this account, was propelled first by what workers were fleeing and only later by what they were seeking.