移民对本地劳动力市场调整的贡献

中文摘要

美国长期存在就业率的持续性区域差距。原则上，这些差距应通过人口流动而被消除。移民能否发挥这一作用？值得注意的是，我表明，自1960年以来，来自国外的新移民占对这些差距的平均人口响应的40%——这一比例远超其在总迁移流量中的历史份额。但尽管如此，移民并未显著加快地方人口调整（或缩小地方就业率差距），因为它挤出了内部流动的贡献。事实上，这种挤出可以帮助解释同期内部流动性的下降。最后，我将这一"超额"的外国贡献归因于一种地方性滚雪球效应，该效应由持续性的地方冲击和移民聚居区的动态所驱动。这一机制对将移民聚居区（普遍地）用作外国流入工具变量的做法提出了挑战。但我并未主张放弃这一工具变量，而是提出了一种（受我的模型启发的）实证策略以克服这些挑战，并证明了其有效性。

Abstract

The US suffers from persistent regional disparities in employment rates. In principle, these disparities should be eliminated by population mobility. Can immigration fulfill this role? Remarkably, since 1960, I show that new migrants from abroad account for 40% of the average population response to these disparities - which vastly exceeds their historic share of gross migratory flows. But despite this, immigration does not significantly accelerate local population adjustment (or reduce local employment rate disparities), as it crowds out the contribution from internal mobility. Indeed, this crowd-out can help account for the concurrent decline in internal mobility. Finally, I attribute the “excess” foreign contribution to a local snowballing effect, driven by persistent local shocks and the dynamics of migrant enclaves. This mechanism raises challenges to the (pervasive) application of migrant enclaves as an instrument for foreign inflows. But rather than abandoning the instrument, I offer an empirical strategy (motivated by my model) to overcome these challenges; and I demonstrate its efficacy.