Compiling graphs for a trade course, and lo what did I see:
Figure 1: US exports of goods and services (blue), and exports ex petroleum products (brown), both as a share of GDP. NBER defined recession dates peak-to-trough shaded gray. Light orange shading denotes Trump administration. Trump’s trade war dated from 2018Q1 (announcement of Section 232 investigations). Source: BEA, NBER and author’s calculations.
So by the eve of the NBER peak (i.e., 2019Q3), exports had fallen by 0.87 percentage points of GDP, and exports ex-oil had fallen by 0.96 percentage points. (If you’re curious, net exports ex-oil had deteriorated 0.2 percentage points over that period).