We study how changes in trade barriers contributed to the dynamics of the US trade balance and real exchange rate between 1980 and 2015 - a period when trade tripled. Using two dynamic trade models, we decompose fluctuations in the trade balance into terms related to trade integration (global and unilateral) and business cycle asymmetries. We find three main results. First, the relatively large US trade deficits as a share of GDP in the 2000s compared to the 1980s mostly reflect a rise in the trade share of GDP. Second, controlling for trade, only about 60% of net trade flows are due to business cycle asymmetries. And third, about two-thirds of the contribution of business-cycle asymmetries are a lagged response. For instance, the short-run Armington elasticity is about 0.2 while the long-run is closer to 1.12 with only 6.9% of the gap closed per quarter. We show that a two-country IRBC model with a dynamic exporting decision, pricing-to-market, and trade cost shocks can account for the dynamics of the US trade balance, real exchange rate, and trade integration. The model clarifies how permanent and transitory changes in trade barriers affect the trade balance and how to identify changes in trade barriers. It shows that uneven trade policy shocks substantially bias Armington elasticity estimates downward. We also show the effect of temporary trade policies on the trade balance depends on whether they induce a trade war.

我们研究了贸易壁垒的变化如何影响 1980 年至 2015 年间美国贸易平衡和实际汇率的动态——贸易增长了两倍。使用两个动态贸易模型，我们将贸易平衡的波动分解为与贸易一体化（全球和单边）和商业周期不对称相关的条款。我们发现三个主要结果。首先，与 1980 年代相比，2000 年代美国贸易逆差占 GDP 的比重较大，这主要反映了贸易占 GDP 的比重上升。其次，控制贸易，只有约 60% 的净贸易流量是由于经济周期不对称造成的。第三，大约三分之二的商业周期不对称贡献是滞后反应。例如，短期阿明顿弹性约为 0.2，而长期接近 1.12，只有 6。每季度缩小 9% 的差距。我们表明，具有动态出口决策、市场定价和贸易成本冲击的两国 IRBC 模型可以解释美国贸易平衡、实际汇率和贸易一体化的动态。该模型阐明了贸易壁垒的永久性和暂时性变化如何影响贸易平衡以及如何识别贸易壁垒的变化。这表明不平衡的贸易政策冲击大大降低了阿明顿弹性估计。我们还表明临时贸易政策对贸易平衡的影响取决于它们是否引发贸易战。该模型阐明了贸易壁垒的永久性和暂时性变化如何影响贸易平衡以及如何识别贸易壁垒的变化。这表明不平衡的贸易政策冲击大大降低了阿明顿弹性估计。我们还表明临时贸易政策对贸易平衡的影响取决于它们是否引发贸易战。该模型阐明了贸易壁垒的永久性和暂时性变化如何影响贸易平衡以及如何识别贸易壁垒的变化。这表明不平衡的贸易政策冲击大大降低了阿明顿弹性估计。我们还表明临时贸易政策对贸易平衡的影响取决于它们是否会引发贸易战。