This paper investigates whether trade facilitation efforts in East Africa have paradoxically “widened borders” by increasing the
effective distance between trading partners despite physical integration. Using a difference-in-differences design that exploits
staggered roll-out of one-stop border posts (OSBPs) and electronic single-window systems (e-SWS) across the East African
Community (EAC) between 2010 and 2022, we combine high-frequency satellite tracking of truck movements with firm-level
customs microdata and household consumption surveys. We find that while average border-crossing times fell by 70 % and trade
costs declined by 12 %, the elasticity of trade flows with respect to distance actually increased: every additional 100 km of inland
transport now reduces trade volumes by 3 % more than before the reforms. Heterogeneous effects reveal that the gains are
concentrated among large, formal firms located within 150 km of OSBPs, whereas small and remote suppliers experience a relative
deterioration in market access. Calibrated general-equilibrium simulations indicate that the distributional shift raises aggregate EAC
welfare by 1.8 %, but it also widens the “economic border” for the bottom quartile of firms by roughly 80 km. These results suggest
that, in the presence of fixed compliance costs and network economies, trade facilitation can strengthen agglomeration forces and
re-draw effective borders rather than simply erase them. Policy designs that bundle hard infrastructure with targeted support to
lagging regions are needed to achieve inclusive integration.