The East African Community (EAC) has invested heavily in One-Stop Border Posts (OSBPs) with the explicit goal of lowering trade
costs and accelerating regional integration. Exploiting newly released micro-data from the EAC’s 2023 OSBP Performance
Measurement Tool and primary survey evidence from four major corridors (Busia, Taveta–Holili, Mutukula and Mirama
Hills–Kagitumba), this paper provides the first comprehensive causal estimates of OSBP impacts on trade flows, firm-level logistics
costs and welfare. Using a difference-in-differences design that exploits staggered OSBP commissioning between 2014 and 2022, we
find that moving from a two-stop to a one-stop regime reduces average border dwell time by 74 % and cuts truck operating costs
along key routes by 9–14 %
. These cost reductions translate into a 12 % rise in monthly trade value and a 5 % increase in the extensive margin of exporting firms
within 18 months of OSBP activation. Consistent with general-equilibrium effects, consumer prices for heavily traded staples fall by
2–3 % in districts adjacent to treated borders, while smallholder market participation rises by six percentage points. Back-of-the-
envelope calculations indicate that the 22 operational OSBPs have generated annual intra-EAC trade gains of USD 1.1 billion—well
above their combined capital cost. Heterogeneity analysis reveals larger gains where pre-OSBP clearance times were longest and
where complementary digital systems (e.g., electronic cargo tracking) were deployed. The results provide robust evidence that
targeted border-management reforms can deliver rapid and sizeable trade-led development dividends in low-income regions.