Pré-publication, Document de travail: In Africa, boundaries delineated during the colonial era now divide young in-dependent states. By applying regression discontinuity designs to a large set of surveys covering the 1986-2001 period, this paper identities many large and significant jumps in welfare at the borders between five West-African countries around Cote d'Ivoire. Border discontinuities mirror the differences between country averages with respect to household income, connection to utilities and education. Country of residence often makes a difference, even if distance to capital city has some attenuating power. The results are consistent with a national integration process that is underway but not yet achieved.